Components with multiple energization elements for biomedical devices

ABSTRACT

Methods and apparatus to form biocompatible energization elements are described. In some embodiments, the methods and apparatus to form the biocompatible energization elements involve forming cavities comprising active cathode chemistry. The active elements of the cathode and anode are sealed with a laminate stack of biocompatible material. In some embodiments, a field of use for the methods and apparatus may include any biocompatible device or product that requires energization elements.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/040,178 filed Aug. 21, 2014, and is a continuation-in-part of U.S.application Ser. No. 13/358,916, filed Jan. 26, 2012 (now U.S. Pat. No.9,110,310), which claims the benefit of U.S. Provisional Application No.61/454,205, filed Mar. 18, 2011.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Methods and apparatus to form biocompatible energization elements aredescribed. In some embodiments, the methods and apparatus to form thebiocompatible energization elements involve forming a separator elementof the energization element. The active elements including anodes,cathodes and electrolytes may be electrochemically connected and mayinteract with the formed separator elements. In some embodiments, afield of use for the methods and apparatus may include any biocompatibledevice or product that requires energization elements.

2. Discussion of the Related Art

Recently, the number of medical devices and their functionality hasbegun to rapidly develop. These medical devices can include, forexample, implantable pacemakers, electronic pills for monitoring and/ortesting a biological function, surgical devices with active components,contact lenses, infusion pumps, and neurostimulators. Addedfunctionality and an increase in performance to the many of theaforementioned medical devices has been theorized and developed.However, to achieve the theorized added functionality, many of thesedevices now require self-contained energization means that arecompatible with the size and shape requirements of these devices, aswell as the energy requirements of the new energized components.

Some medical devices may include components such as semiconductordevices that perform a variety of functions and can be incorporated intomany biocompatible and/or implantable devices. However, suchsemiconductor components require energy and, thus, energization elementsshould preferably also be included in such biocompatible devices. Thetopology and relatively small size of the biocompatible devices createsnovel and challenging environments for the definition of variousfunctionalities. In many embodiments, it is important to provide safe,reliable, compact and cost effective means to energize the semiconductorcomponents within the biocompatible devices. Therefore, a need existsfor novel embodiments of forming biocompatible energization elements forimplantation within or upon biocompatible devices where the structure ofthe battery elements provides enhanced containment for chemicalcomponents of the energization elements as well as improved control overthe quantity of chemical components contained in the energizationelement.

SUMMARY OF THE INVENTION

Accordingly, methods and apparatus to form biocompatible energizationelements are disclosed which afford manufacturing advantages whilecreating structures which may significantly contain the batterychemistry. As well, the structural design may also provide for inherentcontrol of the quantities of the energization elements found within thebattery elements.

One general aspect includes a biocompatible energization element whichmay also include a gap spacer layer. The biocompatible energizationelement may also include at least a first hole located in the gap spacerlayer. The biocompatible energization element may also include a cathodespacer layer, where the cathode spacer layer is attached to the gapspacer layer. The biocompatible energization element may also include atleast a second hole located in the cathode spacer layer, where thesecond hole is aligned to the first hole, and where the second hole issmaller than the first hole such that when the first hole and the secondhole are aligned there is a ridge of cathode spacer layer exposed in thefirst hole. The biocompatible energization element may also include aseparator layer, where the separator layer is placed within the firsthole in the gap spacer layer and is adhered to the ridge of cathodespacer layer. The biocompatible energization element may also include acavity between sides of the second hole and a first surface of theseparator layer, where the cavity is filled with cathode chemicals. Thebiocompatible energization element may also include a first currentcollector coated with anode chemicals. The biocompatible energizationelement may also include a second current collector, where the secondcurrent collector is in electrical connection with the cathodechemicals. The biocompatible energization element may also include anelectrolyte including electrolyte chemicals.

Implementations may include the biocompatible energization element wherethe cathode chemicals, anode chemicals and electrolyte chemicals areconsistent with multiple charging and discharging cycles of theenergization The biocompatible energization element may also includeexamples where the cathode chemicals include a salt of lithium. Thebiocompatible energization element may include lithium iron phosphate.The biocompatible energization element may also include intercalatedmetal atoms. The biocompatible energization element may also includeintercalated lithium atoms. The biocompatible energization element mayalso include one or more of lead, nickel, lithium, cobalt, zinc, sodium,vanadium, silver, or silicon. The biocompatible energization element mayalso include sodium carboxymethyl cellulose. The biocompatibleenergization element may also include examples where the cathodechemicals include one or more of synthetic graphite and carbon black.The biocompatible energization element may also include examples wherethe cathode chemicals include one or more of styrene butadiene rubber.The biocompatible energization element may also include lithiumhexafluorophosate. The biocompatible energization element may includeexamples where the biocompatible energization element is electricallyconnected to an electroactive element within a biomedical device. Thebiocompatible energization element may also include examples where thebiomedical device is an ophthalmic device. In some examples theophthalmic device may be a contact lens.

The biocompatible energization element may also include examples wherethe electrolyte includes lithium hexafluorophosphate. The biocompatibleenergization element may also include examples where the separatorprecursor mixture includes one or more of poly(vinylidene fluoride),poly(dimethylsiloxane), n-n dimethyl acetamide). Additional examples mayalso include glycerol. The biocompatible energization element may alsoinclude the biocompatible energization element where the separatorincludes glycerol in a concentration at least 90 percent and theconcentration may be reduced from a concentration of glycerol in theseparator precursor mixture. The biocompatible energization element maybe included within a biomedical device.

One general aspect includes the biocompatible energization element whichmay be included into an ophthalmic device where the ophthalmic device isa contact lens. The biocompatible energization element may also includea biocompatible energization element including a cathode spacer layer;at least a first hole located in the cathode spacer layer; a firstcurrent collector coated with anode chemicals, where the first currentcollector is attached to a first surface of the cathode spacer layer,and where a first cavity is created between sides of the first hole anda first surface of the first current collector coated with anodechemicals; a separator layer, where the separator layer is formed withinthe first cavity after a separator precursor mixture is dispensed intothe cavity; a second cavity between sides of the first hole and a firstsurface of the separator layer, where the second cavity is filled withcathode chemicals; a second current collector, where the second currentcollector is in electrical connection with the cathode chemicals; and anelectrolyte. Implementations may include biocompatible energizationelements where the cathode chemicals, anode chemicals and electrolytechemicals are consistent with multiple charging and discharging cyclesof the energization element.

One general aspect includes a method of operating a biomedical device,the method including: obtaining a laminate battery device with multipleenergization elements for an biomedical device including poweredcomponents. The laminate battery device includes a cathode spacer layer,a first hole located in the cathode spacer layer, and a first currentcollector coated with anode chemicals, where the first current collectoris attached to a first surface of the cathode spacer layer. The laminatebattery device may include examples where a first cavity is createdbetween sides of the first hole and a first surface of the first currentcollector coated with anode chemicals. The laminate battery device alsoincludes a separator layer, where the separator layer is formed withinthe first cavity after a separator precursor mixture is dispensed intothe cavity. The method also includes a second cavity between sides ofthe first hole and a first surface of the separator layer, where thesecond cavity is filled with cathode chemicals. The method also includesthe laminate battery device which includes a second current collector,where the second current collector is in electrical connection with thecathode chemicals. The method also includes an electrolyte includingelectrolyte chemicals. The method of also includes placing the laminatebattery device into electrical contact with powered components, whereelectrical current from the laminate battery device flows through atleast one electrical transistor, where the at least one electricaltransistor is located within a controller; where at least a first and asecond discrete energization element are located within the laminatebattery device, where the first discrete energization element generatesa first raw battery power and the second discrete energization elementgenerates a second raw battery power; and where a power management unitis electrically connected to the first and the second discreteenergization elements. In some examples, the power management unitreceives the first raw battery power from the first discreteenergization element and the second raw battery power from the seconddiscrete energization element.

The method may further include utilizing the second measurement todetermine a defectiveness of the second discrete energization element.The method may also include an example where the determination is thatthe second discrete energization element is not defective, and in thatcase the switch controller controls a change of state of a second switchconnecting to the second discrete energization element. The method mayalso include examples where the change of state of the second switchconnects the second discrete energization element to the first poweroutput.

One general aspect includes an apparatus for powering a biomedicaldevice; the apparatus may include a laminate battery device withmultiple energization elements for a biomedical device including poweredcomponents. The apparatus may include a cathode spacer layer and a firsthole located in the cathode spacer layer. The apparatus also includes afirst current collector coated with anode chemicals, where the firstcurrent collector is attached to a first surface of the cathode spacerlayer, and where a first cavity is created between sides of the firsthole and a first surface of the first current collector coated withanode chemicals. The apparatus also includes a separator layer, wherethe separator layer is formed within the first cavity after a separatorprecursor mixture is dispensed into the cavity. The apparatus alsoincludes a second cavity between sides of the first hole and a firstsurface of the separator layer, where the second cavity is filled withcathode chemicals. The apparatus also includes a second currentcollector, where the second current collector is in electricalconnection with the cathode chemicals. The apparatus also includes athird current collector, where the third current collector is physicallysegmented from the second current collector and is in electricalconnection with the cathode chemicals within a second hole located inthe cathode spacer layer; and an interconnect junction element, wherethe interconnection junction element makes electrical connection to thefirst current collector, the second current collector and the thirdcurrent collector, where an electrical diode within the interconnectjunction element makes connection to at least one of the first currentcollector, the second current collector and the third current collector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D illustrate exemplary aspects of biocompatible energizationelements in concert with the exemplary application of contact lenses.

FIG. 2 illustrates the exemplary size and shape of individual cells ofan exemplary battery design.

FIG. 3A illustrates a first stand-alone, packaged biocompatibleenergization element with exemplary anode and cathode connections.

FIG. 3B illustrates a second stand-alone, packaged biocompatibleenergization element with exemplary anode and cathode connections.

FIGS. 4A-4N illustrate exemplary method steps for the formation ofbiocompatible energization elements for biomedical devices.

FIG. 5 illustrates an exemplary fully formed biocompatible energizationelement.

FIGS. 6A-6F illustrate exemplary method steps for structural formationof biocompatible energization elements.

FIGS. 7A-7F illustrate exemplary method steps for structural formationof biocompatible energization elements with alternate electroplatingmethod.

FIGS. 8A-8H illustrate exemplary method steps for the formation ofbiocompatible energization elements with hydrogel separator forbiomedical devices.

FIGS. 9A-C illustrate exemplary methods steps for structural formationof biocompatible energization elements utilizing an alternativeseparator processing embodiments.

FIGS. 10A and 10B illustrate exemplary routings of interconnects andjunction elements for multiple energization element devices.

FIGS. 10C through 10E illustrate exemplary cross section depictions ofthe examples of FIGS. 10A and 10B.

FIG. 11 illustrates an exemplary switching system that may be used tocreate multiple power outputs with multiple energization elementdevices.

FIG. 12 illustrates an exemplary device with multiple energizationelements where the elements may be formed as rechargeable elements.

FIG. 13 illustrates an exemplary device with multiple energizationelements where the elements may be formed as single-use elements.

DETAILED DESCRIPTION OF THE INVENTION

Methods and apparatus to form three-dimensional biocompatibleenergization elements are disclosed in this application. The separatorelement within the energization elements may be formed with novelmethods and may comprise novel materials. In the following sections,detailed descriptions of various embodiments are described. Thedescription of both preferred and alternative embodiments are exemplaryembodiments only, and various modifications and alterations may beapparent to those skilled in the art. Therefore, the exemplaryembodiments do not limit the scope of this application. Thethree-dimensional biocompatible energization elements are designed foruse in or proximate to the body of a living organism.

Glossary

In the description and claims below, various terms may be used for whichthe following definitions will apply:

“Anode” as used herein refers to an electrode through which electriccurrent flows into a polarized electrical device. The direction ofelectric current is typically opposite to the direction of electronflow. In other words, the electrons flow from the anode into, forexample, an electrical circuit.

“Binder” as used herein refers to a polymer that is capable ofexhibiting elastic responses to mechanical deformations and that ischemically compatible with other energization element components. Forexample, binders may include electroactive materials, electrolytes,polymers, etc.

“Biocompatible” as used herein refers to a material or device thatperforms with an appropriate host response in a specific application.For example, a biocompatible device does not have toxic or injuriouseffects on biological systems.

“Cathode” as used herein refers to an electrode through which electriccurrent flows out of a polarized electrical device. The direction ofelectric current is typically opposite to the direction of electronflow. Therefore, the electrons flow into the cathode of the polarizedelectrical device, and out of, for example, the connected electricalcircuit.

“Coating” as used herein refers to a deposit of material in thin forms.In some uses, the term will refer to a thin deposit that substantiallycovers the surface of a substrate it is formed upon. In other morespecialized uses, the term may be used to describe small thin depositsin smaller regions of the surface.

“Electrode” as used herein may refer to an active mass in the energysource. For example, it may include one or both of the anode andcathode.

“Energized” as used herein refers to the state of being able to supplyelectrical current or to have electrical energy stored within.

“Energy” as used herein refers to the capacity of a physical system todo work. Many uses of the energization elements may relate to thecapacity of being able to perform electrical actions.

“Energy Source” or “Energization Element” or “Energization Device” asused herein refers to any device or layer which is capable of supplyingenergy or placing a logical or electrical device in an energized state.The energization elements may include batteries. The batteries may beformed from alkaline type cell chemistry and may be solid-statebatteries or wet cell batteries.

“Fillers” as used herein refer to one or more energization elementseparators that do not react with either acid or alkaline electrolytes.Generally, fillers may include substantially water insoluble materialssuch as carbon black; coal dust; graphite; metal oxides and hydroxidessuch as those of silicon, aluminum, calcium, magnesium, barium,titanium, iron, zinc, and tin; metal carbonates such as those of calciumand magnesium; minerals such as mica, montmorollonite, kaolinite,attapulgite, and talc; synthetic and natural zeolites such as Portlandcement; precipitated metal silicates such as calcium silicate; hollow orsolid polymer or glass microspheres, flakes and fibers; etc.

“Functionalized” as used herein refers to making a layer or device ableto perform a function including, for example, energization, activation,and/or control.

“Mold” as used herein refers to a rigid or semi-rigid object that may beused to form three-dimensional objects from uncured formulations. Someexemplary molds include two mold parts that, when opposed to oneanother, define the structure of a three-dimensional object.

“Power” as used herein refers to work done or energy transferred perunit of time.

“Rechargeable” or “Re-energizable” as used herein refer to a capabilityof being restored to a state with higher capacity to do work. Many usesmay relate to the capability of being restored with the ability to flowelectrical current at a certain rate for certain, reestablished timeperiods.

“Reenergize” or “Recharge” as used herein refer to restoring to a statewith higher capacity to do work. Many uses may relate to restoring adevice to the capability to flow electrical current at a certain ratefor a certain reestablished time period.

“Released” as used herein and sometimes referred to as “released from amold” means that a three-dimensional object is either completelyseparated from the mold, or is only loosely attached to the mold, sothat it may be removed with mild agitation.

“Stacked” as used herein means to place at least two component layers inproximity to each other such that at least a portion of one surface ofone of the layers contacts a first surface of a second layer. In someexamples, a coating, whether for adhesion or other functions, may residebetween the two layers that are in contact with each other through saidcoating.

“Traces” as used herein refer to energization element components capableof connecting together the circuit components. For example, circuittraces may include copper or gold when the substrate is a printedcircuit board and may typically be copper, gold or printed film in aflexible circuit. A special type of “Trace” is the current collector.Current collectors are traces with electrochemical compatibility thatmake the current collectors suitable for use in conducting electrons toand from an anode or cathode in the presence of electrolyte.

The methods and apparatus presented herein relate to formingbiocompatible energization elements for inclusion within or on flat orthree-dimensional biocompatible devices. A particular class ofenergization elements may be batteries that are fabricated in layers.The layers may also be classified as laminate layers. A battery formedin this manner may be classified as a laminar battery.

There may be other examples of how to assemble and configure batteriesaccording to the present invention, and some may be described infollowing sections. However, for many of these examples, there areselected parameters and characteristics of the batteries that may bedescribed in their own right. In the following sections, somecharacteristics and parameters will be focused upon.

Exemplary Biomedical Device Construction with Biocompatible EnergizationElements

An example of a biomedical device that may incorporate the EnergizationElements, batteries, of the present invention may be an electroactivefocal-adjusting contact lens. Referring to FIG. 1A, an example of such acontact lens insert is depicted as contact lens insert 100. In thecontact lens insert 100, there may be an electroactive element 120 thatmay accommodate focal characteristic changes in response to controllingvoltages. A circuit 105, to provide those controlling voltage signals aswell as to provide other functions such as controlling sensing of theenvironment for external control signals, may be powered by abiocompatible battery element 110. As depicted in FIG. 1A, the batteryelement 110 may be found as multiple major pieces, in this case threepieces, and may include the various configurations of battery chemistryelements as has been discussed. The battery elements 110 may havevarious interconnect features to join together pieces as may be depictedunderlying the region of interconnect 114. The battery elements 110 maybe connected to a circuit element that may have its own substrate 111upon which interconnect features 125 may be located. The circuit 105,which may be in the form of an integrated circuit, may be electricallyand physically connected to the substrate 111 and its interconnectfeatures 125.

Referring to FIG. 1B, a cross sectional relief of a contact lens 150 maycomprise contact lens insert 100 and its discussed constituents. Thecontact lens insert 100 may be encapsulated into a skirt of contact lenshydrogel 155 which may encapsulate the contact lens insert 100 andprovide a comfortable interface of the contact lens 150 to a user's eye.

In reference to concepts of the present invention, the battery elementsmay be formed in a two-dimensional form as depicted in FIG. 1C. In thisdepiction there may be two main regions of battery cells in the regionsof battery component 165 and the second battery component in the regionof battery chemistry element 160. The battery elements, which aredepicted in flat form in FIG. 1C, may connect to a circuit element 163,which in the example of FIG. 1C may comprise two major circuit areas167. The circuit element 163 may connect to the battery element at anelectrical contact 161 and a physical contact 162. The flat structuremay be folded into a three-dimensional conical structure as has beendescribed with respect to the present invention. In that process asecond electrical contact 166 and a second physical contact 164 may beused to connect and physically stabilize the three-dimensionalstructure. Referring to FIG. 1D, a representation of thisthree-dimensional conical structure 180 is illustrated. The physical andelectrical contact points 181 may also be found and the illustration maybe viewed as a three-dimensional view of the resulting structure. Thisstructure may include the modular electrical and battery component thatwill be incorporated with a lens insert into a biocompatible device.

Segmented Battery Schemes

Referring to FIG. 2, an example of different types of segmented batteryschemes is depicted for an exemplary battery element for a contact lenstype example. The segmented components may be relatively circular-shaped271, square-shaped 272 or rectangular-shaped. In rectangular-shapedexamples, the rectangles may be small rectangular shapes 273, largerrectangular shapes 274, or even larger rectangular shapes 275.

Custom Shapes of Flat Battery Elements

In some examples of biocompatible batteries, the batteries may be formedas flat elements. Referring to FIG. 3A, an example of a rectangularoutline 310 of the battery element is depicted with an anode connection311 and a cathode connection 312. Referring to FIG. 3B, an example of acircular outline 330 of a battery element is depicted with an anodeconnection 331 and a cathode connection 332.

In some examples of flat-formed batteries, the outlines of the batteryform may be dimensionally and geometrically configured to fit in customproducts. In addition to examples with rectangular or circular outlines,custom “free-form” or “free shape” outlines may be formed which mayallow the battery configuration to be optimized to fit within a givenproduct.

In the exemplary biomedical device case of a variable optic, a“free-form” example of a flat outline may be arcuate in form. The freeform may be of such geometry that when formed to a three-dimensionalshape, it may take the form of a conical, annular skirt that fits withinthe constraining confines of a contact lens. It may be clear thatsimilar beneficial geometries may be formed where medical devices haverestrictive 2D or 3D shape requirements.

Biocompatibility Aspects of Batteries

As an example, the batteries according to the present invention may haveimportant aspects relating to safety and biocompatibility. In someexamples, batteries for biomedical devices may need to meet requirementsabove and beyond those for typical usage scenarios. In some examples,design aspects may be considered related to stressing events. Forexample, the safety of an electronic contact lens may need to beconsidered in the event a user breaks the lens during insertion orremoval. In another example, design aspects may consider the potentialfor a user to be struck in the eye by a foreign object. Still furtherexamples of stressful conditions that may be considered in developingdesign parameters and constraints may relate to the potential for a userto wear the lens in challenging environments like the environment underwater or the environment at high altitude in non-limiting examples.

The safety of such a device may be influenced by the materials that thedevice is formed with or from, by the quantities of those materialsemployed in manufacturing the device, and also by the packaging appliedto separate the devices from the surrounding on- or in-body environment.In an example, pacemakers may be a typical type of biomedical devicewhich may include a battery and which may be implanted in a user for anextended period of time. Accordingly, in some examples, such pacemakersmay typically be packaged with welded, hermetic titanium enclosures, orin other examples, multiple layers of encapsulation. Emerging poweredbiomedical devices may present new challenges for packaging, especiallybattery packaging. These new devices may be much smaller than existingbiomedical devices, for example, an electronic contact lens or pillcamera may be significantly smaller than a pacemaker. In such examples,the volume and area available for packaging may be greatly reduced.

Electrical Requirements of Microbatteries

Another area for design considerations may relate to electricalrequirements of the device, which may be provided by the battery. Inorder to function as a power source for a medical device, an appropriatebattery may need to meet the full electrical requirements of the systemwhen operating in a non-connected or non-externally powered mode. Anemerging field of non-connected or non-externally powered biomedicaldevices may include, for example, vision-correcting contact lenses,health monitoring devices, pill cameras, and novelty devices. Recentdevelopments in integrated circuit (IC) technology may permit meaningfulelectrical operation at very low current levels, for example, picoampsof standby current and microamps of operating current. IC's may alsopermit very small devices.

Microbatteries for biomedical applications may be required to meet manysimultaneous, challenging requirements. For example, the microbatterymay be required to have the capability to deliver a suitable operatingvoltage to an incorporated electrical circuit. This operating voltagemay be influenced by several factors including the IC process “node,”the output voltage from the circuit to another device, and a particularcurrent consumption target which may also relate to a desired devicelifetime.

With respect to the IC process, nodes may typically be differentiated bythe minimum feature size of a transistor, such as its “so-called”transistor channel. This physical feature, along with other parametersof the IC fabrication, such as gate oxide thickness, may be associatedwith a resulting rating standard for “turn-on” or “threshold” voltagesof field-effect transistors (FET's) fabricated in the given processnode. For example, in a node with a minimum feature size of 0.5 microns,it may be common to find FET's with turn-on voltages of 5.0V. However,at a minimum feature size of 90 nm, the FET's may turn-on at 1.2, 1.8,and 2.5V. The IC foundry may supply standard cells of digital blocks,for example, inverters and flip-flops that have been characterized andare rated for use over certain voltage ranges. Designers chose an ICprocess node based on several factors including density of digitaldevices, analog/digital mixed signal devices, leakage current, wiringlayers, and availability of specialty devices such as high-voltageFET's. Given these parametric aspects of the electrical components,which may draw power from a microbattery, it may be important for themicrobattery power source to be matched to the requirements of thechosen process node and IC design, especially in terms of availablevoltage and current.

In some examples, an electrical circuit powered by a microbattery, mayconnect to another device. In non-limiting examples, themicrobattery-powered electrical circuit may connect to an actuator or atransducer. Depending on the application, these may include alight-emitting diode (LED), a sensor, a microelectromechanical system(MEMS) pump, or numerous other such devices. In some examples, suchconnected devices may require higher operating voltage conditions thancommon IC process nodes. For example, a variable-focus lens may require35V to activate. The operating voltage provided by the battery maytherefore be a critical consideration when designing such a system. Insome examples of this type of consideration, the efficiency of a lensdriver to produce 35V from a 1V battery may be significantly less thanit might be when operating from a 2V battery. Further requirements, suchas die size, may be dramatically different considering the operatingparameters of the microbattery as well.

Individual battery cells may typically be rated with open-circuit,loaded, and cutoff voltages. The open-circuit voltage is the potentialproduced by the battery cell with infinite load resistance. The loadedvoltage is the potential produced by the cell with an appropriate, andtypically also specified, load impedance placed across the cellterminals. The cutoff voltage is typically a voltage at which most ofthe battery has been discharged. The cutoff voltage may represent avoltage, or degree of discharge, below which the battery should not bedischarged to avoid deleterious effects such as excessive gassing. Thecutoff voltage may typically be influenced by the circuit to which thebattery is connected, not just the battery itself, for example, theminimum operating voltage of the electronic circuit. In one example, analkaline cell may have an open-circuit voltage of 1.6V, a loaded voltagein the range 1.0 to 1.5V, and a cutoff voltage of 1.0V. The voltage of agiven microbattery cell design may depend upon other factors of the cellchemistry employed. And, different cell chemistry may therefore havedifferent cell voltages.

Cells may be connected in series to increase voltage; however, thiscombination may come with tradeoffs to size, internal resistance, andbattery complexity. Cells may also be combined in parallelconfigurations to decrease resistance and increase capacity; however,such a combination may tradeoff size and shelf life.

Battery capacity may be the ability of a battery to deliver current, ordo work, for a period of time. Battery capacity may typically bespecified in units such as microamp-hours. A battery that may deliver 1microamp of current for 1 hour has 1 microamp-hour of capacity. Capacitymay typically be increased by increasing the mass (and hence volume) ofreactants within a battery device; however, it may be appreciated thatbiomedical devices may be significantly constrained on available volume.Battery capacity may also be influenced by electrode and electrolytematerial.

Depending on the requirements of the circuitry to which the battery isconnected, a battery may be required to source current over a range ofvalues. During storage prior to active use, a leakage current on theorder of picoamps to nanoamps may flow through circuits, interconnects,and insulators. During active operation, circuitry may consume quiescentcurrent to sample sensors, run timers, and perform such low powerconsumption functions. Quiescent current consumption may be on the orderof nanoamps to milliamps. Circuitry may also have even higher peakcurrent demands, for example, when writing flash memory or communicatingover radio frequency (RF). This peak current may extend to tens ofmilliamps or more. The resistance and impedance of a microbattery devicemay also be important to design considerations.

Shelf life typically refers to the period of time which a battery maysurvive in storage and still maintain useful operating parameters. Shelflife may be particularly important for biomedical devices for severalreasons. Electronic devices may displace non-powered devices, as forexample may be the case for the introduction of an electronic contactlens. Products in these existing market spaces may have establishedshelf life requirements, for example, three years, due to customer,supply chain, and other requirements. It may typically be desired thatsuch specifications not be altered for new products. Shelf liferequirements may also be set by the distribution, inventory, and usemethods of a device including a microbattery. Accordingly,microbatteries for biomedical devices may have specific shelf liferequirements, which may be, for example, measured in the number ofyears.

In some examples, three-dimensional biocompatible energization elementsmay be rechargeable. For example, an inductive coil may also befabricated on the three-dimensional surface. The inductive coil couldthen be energized with a radio-frequency (“RF”) fob. The inductive coilmay be connected to the three-dimensional biocompatible energizationelement to recharge the energization element when RF is applied to theinductive coil. In another example, photovoltaics may also be fabricatedon the three-dimensional surface and connected to the three-dimensionalbiocompatible energization element. When exposed to light or photons,the photovoltaics will produce electrons to recharge the energizationelement.

In some examples, a battery may function to provide the electricalenergy for an electrical system. In these examples, the battery may beelectrically connected to the circuit of the electrical system. Theconnections between a circuit and a battery may be classified asinterconnects. These interconnects may become increasingly challengingfor biomedical microbatteries due to several factors. In some examples,powered biomedical devices may be very small thus allowing little areaand volume for the interconnects. The restrictions of size and area mayimpact the electrical resistance and reliability of theinterconnections.

In other respects, a battery may contain a liquid electrolyte whichcould boil at high temperature. This restriction may directly competewith the desire to use a solder interconnect which may, for example,require relatively high temperatures such as 250 degrees Celsius tomelt. Although in some examples, the battery chemistry, including theelectrolyte, and the heat source used to form solder basedinterconnects, may be isolated spatially from each other. In the casesof emerging biomedical devices, the small size may preclude theseparation of electrolyte and solder joints by sufficient distance toreduce heat conduction.

Interconnects

Interconnects may allow current to flow to and from the battery inconnection with an external circuit. Such interconnects may interfacewith the environments inside and outside the battery, and may cross theboundary or seal between those environments. These interconnects may beconsidered as traces, making connections to an external circuit, passingthrough the battery seal, and then connecting to the current collectorsinside the battery. As such, these interconnects may have severalrequirements. Outside the battery, the interconnects may resembletypical printed circuit traces. They may be soldered to, or otherwiseconnect to, other traces. In an example where the battery is a separatephysical element from a circuit board comprising an integrated circuit,the battery interconnect may allow for connection to the externalcircuit. This connection may be formed with solder, conductive tape,conductive ink or epoxy, or other means. The interconnect traces mayneed to survive in the environment outside the battery, for example, notcorroding in the presence of oxygen.

As the interconnect passes through the battery seal, it may be ofcritical importance that the interconnect coexist with the seal andpermit sealing. Adhesion may be required between the seal andinterconnect in addition to the adhesion which may be required betweenthe seal and battery package. Seal integrity may need to be maintainedin the presence of electrolyte and other materials inside the battery.Interconnects, which may typically be metallic, may be known as pointsof failure in battery packaging. The electrical potential and/or flow ofcurrent may increase the tendency for electrolyte to “creep” along theinterconnect. Accordingly, an interconnect may need to be engineered tomaintain seal integrity.

Inside the battery, the interconnects may interface with the currentcollectors or may actually form the current collectors. In this regard,the interconnect may need to meet the requirements of the currentcollectors as described herein, or may need to form an electricalconnection to such current collectors.

One class of candidate interconnects and current collectors is metalfoils. Such foils are available in thickness of 25 microns or less,which make them suitable for very thin batteries. Such foil may also besourced with low surface roughness and contamination, two factors whichmay be critical for battery performance. The foils may include zinc,nickel, brass, copper, titanium, other metals, and various alloys.

Electrolyte

An electrolyte is a component of a battery which facilitates a chemicalreaction to take place between the chemical materials of the electrodes.Typical electrolytes may be electrochemically active to the electrodes,for example, allowing oxidation and reduction reactions to occur. Insome examples, this important electrochemical activity may make for achallenge to creating devices that are biocompatible. For example,potassium hydroxide (KOH) may be a commonly used electrolyte in alkalinecells. At high concentration the material has a high pH and may interactunfavorably with various living tissues. On the other hand, in someexamples, electrolytes may be employed which may be lesselectrochemically active; however, these materials may typically resultin reduced electrical performance, such as reduced cell voltage andincreased cell resistance. Accordingly, one key aspect of the design andengineering of a biomedical microbattery may be the electrolyte. It maybe desirable for the electrolyte to be sufficiently active to meetelectrical requirements while also being relatively safe for use in- oron-body.

Various test scenarios may be used to determine the safety of batterycomponents, in particular electrolytes, to living cells. These results,in conjunction with tests of the battery packaging, may allowengineering design of a battery system that may meet requirements. Forexample, when developing a powered contact lens, battery electrolytesmay be tested on a human corneal cell model. These tests may includeexperiments on electrolyte concentration, exposure time, and additives.The results of such tests may indicate cell metabolism and otherphysiological aspects. Tests may also include in-vivo testing on animalsand humans.

Electrolytes for use in the present invention may include zinc chloride,zinc acetate, ammonium acetate, and ammonium chloride in massconcentrations from approximately 0.1 percent to 50 percent, and in anon-limiting example may be approximately 25 percent. The specificconcentrations may depend on electrochemical activity, batteryperformance, shelf life, seal integrity, and biocompatibility.

In some examples, several classes of additives may be utilized in thecomposition of a battery system. Additives may be mixed into theelectrolyte base to alter its characteristics. For example, gellingagents such as agar may reduce the ability of the electrolyte to leakout of packing, thereby increasing safety. Corrosion inhibitors may beadded to the electrolyte, for example, to improve shelf life by reducingthe undesired dissolution of the zinc anode into the electrolyte. Theseinhibitors may positively or adversely affect the safety profile of thebattery. Wetting agents or surfactants may be added, for example, toallow the electrolyte to wet the separator or to be filled into thebattery package. Again, these wetting agents may be positive or negativefor safety. The addition of surfactant to the electrolyte may increasethe electrical impedance of the cell. Accordingly, the lowestconcentration of surfactant to achieve the desired wetting or otherproperties should be used. Exemplary surfactants may include Triton™X-100, Triton™ QS44, and Dowfax™ 3B2 in concentrations from 0.01 percentto 2 percent.

Novel electrolytes are also emerging which may dramatically improve thesafety profile of biomedical microbatteries. For example, a class ofsolid electrolytes may be inherently resistant to leaking while stilloffering suitable electrical performance.

Batteries using “salt water” electrolyte are commonly used in reservecells for marine use. Torpedoes, buoys, and emergency lights may usesuch batteries. Reserve cells are batteries in which the activematerials, the electrodes and electrolyte, are separated until the timeof use. Because of this separation, the cells' self-discharge is greatlyreduced and shelf life is greatly increased. Salt water batteries may bedesigned from a variety of electrode materials, including zinc,magnesium, aluminum, copper, tin, manganese dioxide, and silver oxide.The electrolyte may be actual sea water, for example, water from theocean flooding the battery upon contact, or may be a speciallyengineered saline formulation. This type of battery may be particularlyuseful in contact lenses. A saline electrolyte may have superiorbiocompatibility to classical electrolytes such as potassium hydroxideand zinc chloride. Contact lenses are stored in a “packing solution”which is typically a mixture of sodium chloride, perhaps with othersalts and buffering agents. This solution has been demonstrated as abattery electrolyte in combination with a zinc anode and manganesedioxide cathode. Other electrolyte and electrode combinations arepossible. A contact lens using a “salt water” battery may comprise anelectrolyte based on sodium chloride, packing solution, or even aspecially engineered electrolyte similar to tear fluid. Such a batterycould, for example, be activated with packing solution, maintain anopening to the eye, and continue operating with exposure to human tears.

In addition to, or instead of, possible benefits for biocompatibility byusing an electrolyte more similar to tears, or actually using tears, areserve cell may be used to meet the shelf life requirements of acontact lens product. Typical contact lenses are specified for storageof 3 years or more. This is a challenging requirement for a battery witha small and thin package. A reserve cell for use in a contact lens mayhave a design similar to those shown in FIGS. 1 and 3, but theelectrolyte might not be added at the time of manufacture. Theelectrolyte may be stored in an ampule within the contact lens andconnected to the battery, or saline surrounding the battery may be usedas the electrolyte. Within the contact lens and battery package, a valveor port may be designed to separate the electrolyte from the electrodesuntil the user activates the lens. Upon activation, perhaps by simplypinching the edge of the contact lens (similar to activating a glowstick), the electrolyte may be allowed to flow into the battery and forman ionic pathway between the electrodes. This may involve a one-timetransfer of electrolyte or may expose the battery for continueddiffusion.

Some battery systems may use or consume electrolyte during the chemicalreaction. Accordingly, it may be necessary to engineer a certain volumeof electrolyte into the packaged system. This electrolyte may be storedin various locations including the separator or a reservoir.

In some examples, a design of a battery system may include a componentor components that may function to limit discharge capacity of thebattery system. For example, it may be desirable to design the materialsand amounts of materials of the anode, cathode, or electrolyte such thatone of them may be depleted first during the course of reactions in thebattery system. In such an example, the depletion of one of the anode,cathode, or electrolyte may reduce the potential for problematicdischarge and side reactions to not take place at lower dischargevoltages. These problematic reactions may produce, for example,excessive gas or byproducts which could be detrimental to safety andother factors.

Modular Battery Components

In some examples, a modular battery component may be formed according tosome aspects and examples of the present invention. In these examples,the modular battery assembly may be a separate component from otherparts of the biomedical device. In the example of an ophthalmic contactlens device, such a design may include a modular battery that isseparate from the rest of a media insert. There may be numerousadvantages of forming a modular battery component. For example, in theexample of the contact lens, a modular battery component may be formedin a separate, non-integrated process which may alleviate the need tohandle rigid, three-dimensionally formed optical plastic components. Inaddition, the sources of manufacturing may be more flexible and mayoperate in a more parallel mode to the manufacturing of the othercomponents in the biomedical device. Furthermore, the fabrication of themodular battery components may be decoupled from the characteristics ofthree-dimensional (3D) shaped devices. For example, in applicationsrequiring three-dimensional final forms, a modular battery system may befabricated in a flat or roughly two-dimensional (2D) perspective andthen shaped to the appropriate three-dimensional shape. A modularbattery component may be tested independently of the rest of thebiomedical device and yield loss due to battery components may be sortedbefore assembly. The resulting modular battery component may be utilizedin various media insert constructs that do not have an appropriate rigidregion upon which the battery components may be formed; and, in a stillfurther example, the use of modular battery components may facilitatethe use of different options for fabrication technologies than mightotherwise be utilized, such as, web-based technology (roll to roll),sheet-based technology (sheet-to-sheet), printing, lithography, and“squeegee” processing. In some examples of a modular battery, thediscrete containment aspect of such a device may result in additionalmaterial being added to the overall biomedical device construct. Sucheffects may set a constraint for the use of modular battery solutionswhen the available space parameters require minimized thickness orvolume of solutions.

Battery shape requirements may be driven at least in part by theapplication for which the battery is to be used. Traditional batteryform factors may be cylindrical forms or rectangular prisms, made ofmetal, and may be geared toward products which require large amounts ofpower for long durations. These applications may be large enough thatthey may comprise large form factor batteries. In another example,planar (2D) solid-state batteries are thin rectangular prisms, typicallyformed upon inflexible silicon or glass. These planar solid-statebatteries may be formed in some examples using silicon wafer-processingtechnologies. In another type of battery form factor, low power,flexible batteries may be formed in a pouch construct, using thin foilsor plastic to contain the battery chemistry. These batteries may be madeflat (2D), and may be designed to function when bowed to a modestout-of-plane (3D) curvature.

In some of the examples of the battery applications in the presentinvention where the battery may be employed in a variable optic lens,the form factor may require a three-dimensional curvature of the batterycomponent where a radius of that curvature may be on the order ofapproximately 8.4 mm. The nature of such a curvature may be consideredto be relatively steep and for reference may approximate the type ofcurvature found on a human fingertip. The nature of a relative steepcurvature creates challenging aspects for manufacture. In some examplesof the present invention, a modular battery component may be designedsuch that it may be fabricated in a flat, two-dimensional manner andthen formed into a three-dimensional form of relative high curvature.

Battery Module Thickness

In designing battery components for biomedical applications, tradeoffsamongst the various parameters may be made balancing technical, safetyand functional requirements. The thickness of the battery component maybe an important and limiting parameter. For example, in an optical lensapplication the ability of a device to be comfortably worn by a user mayhave a critical dependence on the thickness across the biomedicaldevice. Therefore, there may be critical enabling aspects in designingthe battery for thinner results. In some examples, battery thickness maybe determined by the combined thicknesses of top and bottom sheets,spacer sheets, and adhesive layer thicknesses. Practical manufacturingaspects may drive certain parameters of film thickness to standardvalues in available sheet stock. In addition, the films may have minimumthickness values to which they may be specified base upon technicalconsiderations relating to chemical compatibility, moisture/gasimpermeability, surface finish, and compatibility with coatings that maybe deposited upon the film layers.

In some examples, a desired or goal thickness of a finished batterycomponent may be a component thickness that is less than 220 μm. Inthese examples, this desired thickness may be driven by thethree-dimensional geometry of an exemplary ophthalmic lens device wherethe battery component may need to be fit inside the available volumedefined by a hydrogel lens shape given end user comfort,biocompatibility, and acceptance constraints. This volume and its effecton the needs of battery component thickness may be a function of totaldevice thickness specification as well as device specification relatingto its width, cone angle, and inner diameter. Another important designconsideration for the resulting battery component design may relate tothe volume available for active battery chemicals and materials in agiven battery component design with respect to the resulting chemicalenergy that may result from that design. This resulting chemical energymay then be balanced for the electrical requirements of a functionalbiomedical device for its targeted life and operating conditions

Battery Module Flexibility

Another dimension of relevance to battery design and to the design ofrelated devices that utilize battery based energy sources is theflexibility of the battery component. There may be numerous advantagesconferred by flexible battery forms. For example, a flexible batterymodule may facilitate the previously mentioned ability to fabricate thebattery form in a two-dimensional (2D) flat form. The flexibility of theform may allow the two-dimensional battery to then be formed into anappropriate 3D shape to fit into a biomedical device such as a contactlens.

In another example of the benefits that may be conferred by flexibilityin the battery module, if the battery and the subsequent device isflexible then there may be advantages relating to the use of the device.In an example, a contact lens form of a biomedical device may haveadvantages for insertion/removal of the media insert based contact lensthat may be closer to the insertion/removal of a standard, non-filledhydrogel contact lens.

The number of flexures may be important to the engineering of thebattery. For example, a battery which may only flex one time from aplanar form into a shape suitable for a contact lens may havesignificantly different design from a battery capable of multipleflexures. The flexure of the battery may also extend beyond the abilityto mechanically survive the flexure event. For example, an electrode maybe physically capable of flexing without breaking, but the mechanicaland electrochemical properties of the electrode may be altered byflexure. Flex-induced changes may appear instantly, for example, aschanges to impedance, or flexure may introduce changes which are onlyapparent in long-term shelf life testing.

Battery Module Width

There may be numerous applications into which the biocompatibleenergization elements or batteries of the present invention may beutilized. In general, the battery width requirement may be largely afunction of the application in which it is applied. In an exemplarycase, a contact lens battery system may have constrained needs for thespecification on the width of a modular battery component. In someexamples of an ophthalmic device where the device has a variable opticfunction powered by a battery component, the variable optic portion ofthe device may occupy a central spherical region of about 7.0 mm indiameter. The exemplary battery elements may be considered as athree-dimensional object, which fits as an annular, conical skirt aroundthe central optic and formed into a truncated conical ring. If therequired maximum diameter of the rigid insert is a diameter of 8.50 mm,and tangency to a certain diameter sphere may be targeted (as forexample in a roughly 8.40 mm diameter), then geometry may dictate whatthe allowable battery width may be. There may be geometric models thatmay be useful for calculating desirable specifications for the resultinggeometry which in some examples may be termed a conical frustumflattened into a sector of an annulus.

Flattened battery width may be driven by two features of the batteryelement, the active battery components and seal width. In some examplesrelating to ophthalmic devices a target thickness may be between 0.100mm and 0.500 mm per side, and the active battery components may betargeted at roughly 0.800 mm wide. Other biomedical devices may havediffering design constraints but the principles for flexible flatbattery elements may apply in similar fashion.

Cavities as Design Elements in Battery Component Design

In some examples, battery elements may be designed in manners thatsegment the regions of active battery chemistry. There may be numerousadvantages from the division of the active battery components intodiscrete segments. In a non-limiting example, the fabrication ofdiscrete and smaller elements may facilitate production of the elements.The function of battery elements including numerous smaller elements maybe improved. Defects of various kinds may be segmented andnon-functional elements may be isolated in some cases to result indecreased loss of function. This may be relevant in examples where theloss of battery electrolyte may occur. The isolation of individualizedcomponents may allow for a defect that results in leakage of electrolyteout of the critical regions of the battery to limit the loss of functionto that small segment of the total battery element whereas theelectrolyte loss through the defect could empty a significantly largerregion for batteries configured as a single cell. Smaller cells mayresult in lowered volume of active battery chemicals on an overallperspective, but the mesh of material surrounding each of the smallercells may result in a strengthening of the overall structure.

Battery Element Internal Seals

In some examples of battery elements for use in biomedical devices, thechemical action of the battery involves aqueous chemistry, where wateror moisture is an important constituent to control. Therefore it may beimportant to incorporate sealing mechanisms that retard or prevent themovement of moisture either out of or into the battery body. Moisturebarriers may be designed to keep the internal moisture level at adesigned level, within some tolerance. In some examples, a moisturebarrier may be divided into two sections or components; namely, thepackage and the seal.

The package may refer to the main material of the enclosure. In someexamples, the package may comprise a bulk material. The Water VaporTransmission Rate (WVTR) may be an indicator of performance, with ISO,ASTM standards controlling the test procedure, including theenvironmental conditions operant during the testing. Ideally, the WVTRfor a good battery package may be “zero.” Exemplary materials with anear-zero WVTR may be glass and metal foils. Plastics, on the otherhand, may be inherently porous to moisture, and may vary significantlyfor different types of plastic. Engineered materials, laminates, orco-extrudes may usually be hybrids of the common package materials.

The seal may be the interface between two of the package surfaces. Theconnecting of seal surfaces finishes the enclosure along with thepackage. In many examples, the nature of seal designs may make themdifficult to characterize for the seal's WVTR due to difficulty inperforming measurements using an ISO or ASTM standard, as the samplesize or surface area may not be compatible with those procedures. Insome examples, a practical manner to testing seal integrity may be afunctional test of the actual seal design, for some defined conditions.Seal performance may be a function of the seal material, the sealthickness, the seal length, the seal width, and the seal adhesion orintimacy to package substrates.

In some examples, seals may be formed by a welding process that mayinvolve thermal, laser, solvent, friction, ultrasonic, or arcprocessing. In other examples, seals may be formed through the use ofadhesive sealants such as glues, epoxies, acrylics, natural rubber, andsynthetic rubber. Other examples may derive from the utilization ofgasket type material that may be formed from cork, natural and syntheticrubber, polytetrafluoroethylene (PTFE), polypropylene, and silicones tomention a few non-limiting examples.

In some examples, the batteries according to the present invention maybe designed to have a specified operating life. The operating life maybe estimated by determining a practical amount of moisture permeabilitythat may be obtained using a particular battery system and thenestimating when such a moisture leakage may result in an end of lifecondition for the battery. For example, if a battery is stored in a wetenvironment, then the partial pressure difference between inside andoutside the battery will be minimal, resulting in a reduced moistureloss rate, and therefore the battery life may be extended. The sameexemplary battery stored in a particularly dry and hot environment mayhave a significantly reduced expectable lifetime due to the strongdriving function for moisture loss.

Battery Element Separators

Batteries of the type described in the present invention may utilize aseparator material that physically and electrically separates the anodeand anode current collector portions from the cathode and cathodecurrent collector portions. The separator may be a membrane that ispermeable to water and dissolved electrolyte components; however, it maytypically be electrically non-conductive. While a myriad ofcommercially-available separator materials may be known to those ofskill in the art, the novel form factor of the present invention maypresent unique constraints on the task of separator selection,processing, and handling.

Since the designs of the present invention may have ultra-thin profiles,the choice may be limited to the thinnest separator materials typicallyavailable. For example, separators of approximately 25 microns inthickness may be desirable. Some examples which may be advantageous maybe about 12 microns in thickness. There may be numerous acceptablecommercial separators include microfibrillated, microporous polyethylenemonolayer and/or polypropylene-polyethylene-polypropylene (PP/PE/PP)trilayer separator membranes such as those produced by Celgard(Charlotte, N.C.). A desirable example of separator material may beCelgard M824 PP/PE/PP trilayer membrane having a thickness of 12microns. Alternative examples of separator materials useful for examplesof the present invention may include separator membranes includingregenerated cellulose (e.g. cellophane).

While PP/PE/PP trilayer separator membranes may have advantageousthickness and mechanical properties, owing to their polyolefiniccharacter, they may also suffer from a number of disadvantages that mayneed to be overcome in order to make them useful in examples of thepresent invention. Roll or sheet stock of PP/PE/PP trilayer separatormaterials may have numerous wrinkles or other form errors that may bedeleterious to the micron-level tolerances applicable to the batteriesdescribed herein. Furthermore, polyolefin separators may need to be cutto ultra-precise tolerances for inclusion in the present designs, whichmay therefore implicate laser cutting as an exemplary method of formingdiscrete current collectors in desirable shapes with tight tolerances.Owing to the polyolefinic character of these separators, certain cuttinglasers useful for micro fabrication may employ laser wavelengths, e.g.355 nm, that will not cut polyolefins. The polyolefins do notappreciably absorb the laser energy and are thereby non-ablatable.Finally, polyolefin separators may not be inherently wettable to aqueouselectrolytes used in the batteries described herein.

Nevertheless, there may be methods for overcoming these inherentlimitations for polyolefinic type membranes. In order to present amicroporous separator membrane to a high-precision cutting laser forcutting pieces into arc segments or other advantageous separatordesigns, the membrane may need to be flat and wrinkle-free. If these twoconditions are not met, the separator membrane may not be fully cutbecause the cutting beam may be inhibited as a result of defocusing ofor otherwise scattering the incident laser energy. Additionally, if theseparator membrane is not flat and wrinkle-free, the form accuracy andgeometric tolerances of the separator membrane may not be sufficientlyachieved. Allowable tolerances for separators of current examples maybe, for example, +0 microns and −20 microns with respect tocharacteristic lengths and/or radii. There may be advantages for tightertolerances of +0 microns and −10 micron and further for tolerances of +0microns and −5 microns. Separator stock material may be made flat andwrinkle-free by temporarily laminating the material to a float glasscarrier with an appropriate low-volatility liquid. Low-volatilityliquids may have advantages over temporary adhesives due to thefragility of the separator membrane and due to the amount of processingtime that may be required to release separator membrane from an adhesivelayer. Furthermore, in some examples achieving a flat and wrinkle-freeseparator membrane on float glass using a liquid has been observed to bemuch more facile than using an adhesive. Prior to lamination, theseparator membrane may be made free of particulates. This may beachieved by ultrasonic cleaning of separator membrane to dislodge anysurface-adherent particulates. In some examples, handling of a separatormembrane may be done in a suitable, low-particle environment such as alaminar flow hood or a cleanroom of at least class 10,000. Furthermore,the float glass substrate may be made to be particulate free by rinsingwith an appropriate solvent, ultrasonic cleaning, and/or wiping withclean room wipes.

While a wide variety of low-volatility liquids may be used for themechanical purpose of laminating microporous polyolefin separatormembranes to a float glass carrier, specific requirements may be imposedon the liquid to facilitate subsequent laser cutting of discreteseparator shapes. One requirement may be that the liquid has a surfacetension low enough to soak into the pores of the separator materialwhich may easily be verified by visual inspection. In some examples, theseparator material turns from a white color to a translucent appearancewhen liquid fills the micropores of the material. It may be desirable tochoose a liquid that may be benign and “safe” for workers that will beexposed to the preparation and cutting operations of the separator. Itmay be desirable to choose a liquid whose vapor pressure may be lowenough so that appreciable evaporation does not occur during the timescale of processing (on the order of 1 day). Finally, in some examplesthe liquid may have sufficient solvating power to dissolve advantageousUV absorbers that may facilitate the laser cutting operation. In anexample, it has been observed that a 12 percent (w/w) solution ofavobenzone UV absorber in benzyl benzoate solvent may meet theaforementioned requirements and may lend itself to facilitating thelaser cutting of polyolefin separators with high precision and tolerancein short order without an excessive number of passes of the cuttinglaser beam. In some examples, separators may be cut with an 8 W 355 nmnanosecond diode-pumped solid state laser using this approach where thelaser may have settings for low power attenuation (e.g. 3 percentpower), a moderate speed of 1 to 10 mm/s, and only 1 to 3 passes of thelaser beam. While this UV-absorbing oily composition has been proven tobe an effective laminating and cutting process aid, other oilyformulations may be envisaged by those of skill in the art and usedwithout limitation.

In some examples, a separator may be cut while fixed to a float glass.One advantage of laser cutting separators while fixed to a float glasscarrier may be that a very high number density of separators may be cutfrom one separator stock sheet much like semiconductor die may bedensely arrayed on a silicon wafer. Such an approach may provide economyof scale and parallel processing advantages inherent in semiconductorprocesses. Furthermore, the generation of scrap separator membrane maybe minimized. Once separators have been cut, the oily process aid fluidmay be removed by a series of extraction steps with miscible solvents,the last extraction may be performed with a high-volatility solvent suchas isopropyl alcohol in some examples. Discrete separators, onceextracted, may be stored indefinitely in any suitable low-particleenvironment.

As previously mentioned polyolefin separator membranes may be inherentlyhydrophobic and may need to be made wettable to aqueous surfactants usedin the batteries of the present invention. One approach to make theseparator membranes wettable may be oxygen plasma treatment. Forexample, separators may be treated for 1 to 5 minutes in a 100 percentoxygen plasma at a wide variety of power settings and oxygen flow rates.While this approach may improve wettability for a time, it may bewell-known that plasma surface modifications provide a transient effectthat may not last long enough for robust wetting of electrolytesolutions. Another approach to improve wettability of separatormembranes may be to treat the surface by incorporating a suitablesurfactant on the membrane. In some cases, the surfactant may be used inconjunction with a hydrophilic polymeric coating that remains within thepores of the separator membrane.

Another approach to provide more permanence to the hydrophilicityimparted by an oxidative plasma treatment may be by subsequent treatmentwith a suitable hydrophilic organosilane. In this manner, the oxygenplasma may be used to activate and impart functional groups across theentire surface area of the microporous separator. The organosilane maythen covalently bond to and/or non-covalently adhere to the plasmatreated surface. In examples using an organosilane, the inherentporosity of the microporous separator may not be appreciably changed,monolayer surface coverage may also be possible and desired. Prior artmethods incorporating surfactants in conjunction with polymeric coatingsmay require stringent controls over the actual amount of coating appliedto the membrane, and may then be subject to process variability. Inextreme cases, pores of the separator may become blocked, therebyadversely affecting utility of the separator during the operation of theelectrochemical cell. An exemplary organosilane useful in the presentinvention may be (3-aminopropyl)triethoxysilane. Other hydrophilicorganosilanes may be known to those of skill in the art and may be usedwithout limitation.

Still another method for making separator membranes wettable by aqueouselectrolyte may be the incorporation of a suitable surfactant in theelectrolyte formulation. One consideration in the choice of surfactantfor making separator membranes wettable may be the effect that thesurfactant may have on the activity of one or more electrodes within theelectrochemical cell, for example, by increasing the electricalimpedance of the cell. In some cases, surfactants may have advantageousanti-corrosion properties, specifically in the case of zinc anodes inaqueous electrolytes. Zinc may be an example known to undergo a slowreaction with water to liberate hydrogen gas, which may be undesirable.Numerous surfactants may be known by those of skill in the art to limitrates of said reaction to advantageous levels. In other cases, thesurfactant may so strongly interact with the zinc electrode surface thatbattery performance may be impeded. Consequently, much care may need tobe made in the selection of appropriate surfactant types and loadinglevels to ensure that separator wettability may be obtained withoutdeleteriously affecting electrochemical performance of the cell. In somecases, a plurality of surfactants may be used, one being present toimpart wettability to the separator membrane and the other being presentto facilitate anti-corrosion properties to the zinc anode. In oneexample, no hydrophilic treatment is done to the separator membrane anda surfactant or plurality of surfactants is added to the electrolyteformulation in an amount sufficient to effect wettability of theseparator membrane.

Discrete separators may be integrated into the laminar microbattery bydirect placement into a means for storage including a designed cavity,pocket, or structure within the assembly. Desirably, this storage meansmay be formed by a laminar structure having a cutout, which may be ageometric offset of the separator shape, resulting in a cavity, pocket,or structure within the assembly. Furthermore, the storage means mayhave a ledge or step on which the separator rests during assembly. Theledge or step may optionally include a pressure-sensitive adhesive whichretains the discrete separator. Advantageously, the pressure-sensitiveadhesive may be the same one used in the construction and stack up ofother elements of an exemplary laminar microbattery.

Pressure Sensitive Adhesive

In some examples, the plurality of components composing the laminarmicrobatteries of the present invention may be held together with apressure-sensitive adhesive (PSA) that also serves as a sealant. While amyriad of commercially available pressure-sensitive adhesiveformulations may exist, such formulations almost always includecomponents that may make them unsuitable for use within a biocompatiblelaminar microbattery. Examples of undesirable components inpressure-sensitive adhesives may include low molecular mass leachablecomponents, antioxidants e.g. BHT and/or MEHQ, plasticizing oils,impurities, oxidatively unstable moieties containing, for example,unsaturated chemical bonds, residual solvents and/or monomers,polymerization initiator fragments, polar tackifiers, and the like.

Suitable PSAs may on the other hand exhibit the following properties.They may be able to be applied to laminar components to achieve thinlayers on the order of 2 to 20 microns. As well, they may comprise aminimum of, for example, zero undesirable or non-biocompatiblecomponents. Additionally, they may have sufficient adhesive and cohesiveproperties so as to bind the components of the laminar battery together.And, they may be able to flow into the micron-scale features inherent indevices of the present construction while providing for a robust sealingof electrolyte within the battery. In some examples of suitable PSAs,the PSAs may have a low permeability to water vapor in order to maintaina desirable aqueous electrolyte composition within the battery even whenthe battery may be subjected to extremes in humidity for extendedperiods of time. The PSAs may have good chemical resistance tocomponents of electrolytes such as acids, surfactants, and salts. Theymay be inert to the effects of water immersion. Suitable PSAs may have alow permeability to oxygen to minimize the rate of direct oxidation,which may be a form of self-discharge, of zinc anodes. And, they mayfacilitate a finite permeability to hydrogen gas, which may be slowlyevolved from zinc anodes in aqueous electrolytes. This property offinite permeability to hydrogen gas may avoid a build-up of internalpressure.

In consideration of these requirements, polyisobutylene (PIB) may be acommercially-available material that may be formulated into PSAcompositions meeting many if not all desirable requirements.Furthermore, PIB may be an excellent barrier sealant with very low waterabsorbance and low oxygen permeability. An example of PIB useful in theexamples of the present invention may be Oppanol® B15 by BASFCorporation. Oppanol® B15 may be dissolved in hydrocarbon solvents suchas toluene, heptane, dodecane, mineral spirits, and the like. Oneexemplary PSA composition may include 30 percent Oppanol® B15 (w/w) in asolvent mixture including 70 percent (w/w) toluene and 30 percentdodecane. The adhesive and rheological properties of PIB based PSA's maybe determined in some examples by the blending of different molecularmass grades of PIB. A common approach may be to use a majority of lowmolar mass PIB, e.g. Oppanol® B10 to affect wetting, tack, and adhesion,and to use a minority of high molar mass PIB to effect toughness andresistance to flow. Consequently, blends of any number of PIB molar massgrades may be envisioned and may be practiced within the scope of thepresent invention. Furthermore, tackifiers may be added to the PSAformulation so long as the aforementioned requirements may be met. Bytheir very nature, tackifiers impart polar properties to PSAformulations, so they may need to be used with caution so as to notadversely affect the barrier properties of the PSA. Furthermore,tackifiers may in some cases be oxidatively unstable and may include anantioxidant, which could leach out of the PSA. For these reasons,exemplary tackifiers for use in PSA's for biocompatible laminarmicrobatteries may include fully- or mostly hydrogenated hydrocarbonresin tackifiers such as the Regalrez series of tackifiers from EastmanChemical Corporation.

Additional Package and Substrate Considerations in Biocompatible BatteryModules

There may be numerous packaging and substrate considerations that maydictate desirable characteristics for package designs used inbiocompatible laminar microbatteries. For example, the packaging maydesirably be predominantly foil and/or film based where these packaginglayers may be as thin as possible, for example, 10 to 50 microns.Additionally, the packaging may provide a sufficient diffusion barrierto moisture gain or loss during the shelf life. In many desirableexamples, the packaging may provide a sufficient diffusion barrier tooxygen ingress to limit degradation of zinc anodes by direct oxidation.

In some examples, the packaging may provide a finite permeation pathwayto hydrogen gas that may evolve due to direct reduction of water byzinc. And, the packaging may desirably sufficiently contain and mayisolate the contents of the battery such that potential exposure to auser may be minimized.

In the present invention, packaging constructs may include the followingtypes of functional components: top and bottom packaging layers, PSAlayers, spacer layers, interconnect zones, filling ports, and secondarypackaging.

In some examples, top and bottom packaging layers may comprise metallicfoils or polymer films. Top and bottom packaging layers may comprisemulti-layer film constructs containing a plurality of polymer and/orbarrier layers. Such film constructs may be referred to as coextrudedbarrier laminate films. An example of a commercial coextruded barrierlaminate film of particular utility in the present invention may be 3M®Scotchpak 1109 backing which consists of a polyethylene terephthalate(PET) carrier web, a vapor-deposited aluminum barrier layer, and apolyethylene layer including a total average film thickness of 33microns. Numerous other similar multilayer barrier films may beavailable and may be used in alternate examples of the presentinvention.

In design constructions including a PSA, packaging layer surfaceroughness may be of particular importance because the PSA may also needto seal opposing packaging layer faces. Surface roughness may resultfrom manufacturing processes used in foil and film production, forexample, processes employing rolling, extruding, embossing and/orcalendaring, among others. If the surface is too rough, PSA may be notable to be applied in a uniform thickness when the desired PSA thicknessmay be on the order of the surface roughness Ra (the arithmetic averageof the roughness profile). Furthermore, PSA's may not adequately sealagainst an opposing face if the opposing face has roughness that may beon the order of the PSA layer thickness. In the present invention,packaging materials having a surface roughness, Ra, less than 10 micronsmay be acceptable examples. In some examples, surface roughness valuesmay be 5 microns or less. And, in still further examples, the surfaceroughness may be 1 micron or less. Surface roughness values may bemeasured by a variety of methods including but not limited tomeasurement techniques such as white light interferometry, stylusprofilometry, and the like. There may be many examples in the art ofsurface metrology that surface roughness may be described by a number ofalternative parameters and that the average surface roughness, Ra,values discussed herein may be meant to be representative of the typesof features inherent in the aforementioned manufacturing processes.

Exemplary Illustrated Processing of Biocompatible EnergizationElements—Placed Separator

An example of the steps that may be involved in processing biocompatibleenergization elements may be found referring to FIGS. 4A-4N. Theprocessing at some of the exemplary steps may be found in the individualfigures. In FIG. 4A, an exemplary combination of a PET Cathode Spacer401 and a PET Gap Spacer 404 is illustrated. The PET Cathode Spacer 401may be formed by applying films of PET 403 which, for example, may beroughly 3 mils thick. On either side of the PET layer may be found PSAlayers or these may be capped with a PVDF release layer 402 which may beroughly 1 mil in thickness. The PET Gap spacer 404 may be formed of aPVDF layer 409 which may be roughly 3 mils in thickness. There may be acapping PET layer 405 which may be roughly 0.5 mils in thickness.Between the PVDF layer 409 and the capping PET layer 405, in someexamples, may be a layer of PSA.

Proceeding to FIG. 4B, a hole 406 in the PET Gap spacer layer 404 may becut by laser cutting treatment. Next at FIG. 4C, the cut PET Gap spacerlayer 404 may be laminated 408 to the PET Cathode Spacer layer 401.Proceeding to FIG. 4D, a cathode spacer hole 410 may be cut by lasercutting treatment. The alignment of this cutting step may be registeredto the previously cut features in the PET Gap spacer layer 404. At FIG.4E, a layer of Celgard 412, for an ultimate separator layer, may bebonded to a carrier 411. Proceeding to FIG. 4F, the Celgard material maybe cut to figures that are between the size of the previous two lasercut holes, and approximately the size of the hole 406 in the PET gapspacer, forming a precut separator 420. Proceeding to FIG. 4G, a pickand place tool 421 may be used to pick and place discrete pieces ofCelgard into their desired locations on the growing device. At FIG. 4H,the placed Celgard pieces 422 are fastened into place and then the PVDFrelease layer 423 may be removed. Proceeding to FIG. 4I, the growingdevice structure may be bonded to a film of the anode 425. The anode 425may comprise an anode collector film upon which a zinc anode film hasbeen electrodeposited.

Proceeding to FIG. 4J, a cathode slurry 430 may be placed into theformed gap. A squeegee 431 may be used in some examples to spread thecathode mix across a work piece and in the process fill the gaps of thebattery devices being formed. After filling, the remaining PVDF releaselayer 432 may be removed which may result in the structure illustratedin FIG. 4K. At FIG. 4L the entire structure may be subjected to a dryingprocess which may shrink the cathode slurry 440 to also be at the heightof the PET layer top. Proceeding to FIG. 4M, a cathode film layer 450,which may already have the cathode collector film upon it, may be bondedto the growing structure. In a final illustration at FIG. 4N a lasercutting process may be performed to remove side regions 460 and yield abattery element 470. There may be numerous alterations, deletions,changes to materials and thickness targets that may be useful within theintent of the present invention.

The result of the exemplary processing may be depicted in some detail atFIG. 5. In an example, the following reference features may be defined.The Cathode chemistry 510 may be located in contact with the cathode andcathode collector 520. A pressure-sensitive adhesive layer 530 may holdand seal the cathode collector 520 to a PET Spacer layer 540. On theother side of the PET Spacer layer 540, may be another PSA layer 550,which seals and adheres the PET Spacer layer 540 to the PET Gap layer560. Another PSA layer 565 may seal and adhere the PET Gap layer 560 tothe Anode and Anode Current Collector layers. A Zinc Plated layer 570may be plated onto the Anode Current Collector 580. The separator layer590 may be located within the structure to perform the associatedfunctions as have been defined in the present invention. In someexamples, an electrolyte may be added during the processing of thedevice, in other examples, the separator may already includeelectrolyte.

Exemplary Processing Illustration of Biocompatible EnergizationElements—Deposited Separator

An example of the steps that may be involved in processing biocompatibleenergization elements may be found in FIGS. 6A-6F. The processing atsome of the exemplary steps may be found in the individual figures.There may be numerous alterations, deletions, changes to materials andthickness targets that may be useful within the intent of the presentinvention.

In FIG. 6A, an exemplary laminar construct 600 is illustrated. Thelaminar structure may comprise two laminar construct release layers, 602and 602 a; two laminar construct adhesive layers 604 and 604 a, locatedbetween the laminar construct release layers 602 and 602 a; and alaminar construct core 606, located between the two laminar constructadhesive layers 604 and 604 a. The laminar construct release layers, 602and 602 a, and adhesive layers, 604 and 604 a, may be produced orpurchased, such as a commercially available pressure-sensitive adhesivetransfer tape with primary liner layer. The laminar construct adhesivelayers may be a PVDF layer which may be approximately 1-3 millimeters inthickness and cap the laminar construct core 606. The laminar constructcore 606 may comprise a thermoplastic polymer resin such as polyethyleneterephthalate, which, for example, may be roughly 3 millimeters thick.Proceeding to FIG. 6B, a means for storing the cathode mixture, such asa cavity for the cathode pocket 608, may be cut in the laminar constructby laser cutting treatment.

Next, at FIG. 6C, the bottom laminar construct release layer 602 a maybe removed from the laminar construct, exposing the laminar constructadhesive layer 604 a. The laminar construct adhesive layer 604 a maythen be used to adhere an anode connection foil 610 to cover the bottomopening of the cathode pocket 608. Proceeding to FIG. 6D, the anodeconnection foil 610 may be protected on the exposed bottom layer byadhering a masking layer 612. The masking layer 612 may be acommercially available PSA transfer tape with a primary liner. Next, atFIG. 6E, the anode connection foil 610 may be electroplated with acoherent metal 614, zinc, for example, which coats the exposed sectionof the anode connection foil 610 inside of the cathode pocket.Proceeding to 6F, the anode electrical collection masking layer 612 isremoved from the bottom of the anode connection foil 610 afterelectroplating.

FIGS. 7A-7F illustrate an alternate mode of processing the stepsillustrated in FIGS. 6A-6F. FIGS. 7A-7B illustrate similar processes asdepicted in FIGS. 6A-6B. The laminar structure may comprise two laminarconstruct release layers, 702 and 702 a, one layer on either end; twolaminar construct adhesive layers, 704 and 704 a, located between thelaminar construct release layers 702 and 702 a; and a laminar constructcore 706, located between the two laminar construct adhesive layers 704and 704 a. The laminar construct release layers and adhesive layers maybe produced or purchased, such as a commercially availablepressure-sensitive adhesive transfer tape with primary liner layer. Thelaminar construct adhesive layers may be a polyvinylidene fluoride(PVDF) layer which may be approximately 1-3 millimeters in thickness andcap the laminar construct core 706. The laminar construct core 706 maycomprise a thermoplastic polymer resin such as polyethyleneterephthalate, which, for example, may be roughly 3 millimeters thick.Proceeding to FIG. 7B, a storage means, such as a cavity, for thecathode pocket 708, may be cut in the laminar construct by laser cuttingtreatment. In FIG. 7C, an anode connection foil 710 may be obtained anda protective masking layer 712 applied to one side. Next, at FIG. 7D,the anode connection foil 710 may be electroplated with a layer 714 of acoherent metal, for example, zinc. Proceeding to FIG. 7E, the laminarconstructs of FIGS. 7B and 7D may be combined to form a new laminarconstruct as depicted in FIG. 7E by adhering the construct of FIG. 7B tothe electroplated layer 714 of FIG. 7D. The release layer 702 a of FIG.7B may be removed in order to expose adhesive layer 704 a of FIG. 7B foradherence onto electroplated layer 714 of FIG. 7D. Proceeding next toFIG. 7F, the anode protective masking layer 712 may be removed from thebottom of the anode connection foil 710.

FIGS. 8A-8H may illustrate implementation of energization elements to abiocompatible laminar structure, which at times is referred to as alaminar assembly or a laminate assembly herein, similar to, for example,those illustrated in FIGS. 6A-6F and 7A-7F. Proceeding to FIG. 8A, ahydrogel separator precursor mixture 820 may be deposited on the surfaceof the laminate assembly. In some examples, as depicted, the hydrogelprecursor mixture 820 may be applied up a release layer 802. Next, atFIG. 8B, the hydrogel separator precursor mixture 820 may be squeegeed850 into the cathode pocket while being cleaned off of the release layer802. The term “squeegeed” may generally refer to the use of aplanarizing or scraping tool to rub across the surface and move fluidmaterial over the surface and into cavities as they exist. The processof squeegeeing may be performed by equipment similar to the vernacular“Squeegee” type device or alternatively and planarizing device such asknife edges, razor edges and the like which may be made of numerousmaterials as may be chemically consistent with the material to be moved.

The processing depicted at FIG. 8B may be performed several times toensure coating of the cathode pocket, and increment the thickness ofresulting features. Next, at FIG. 8C, the hydrogel separator precursormixture may be allowed to dry in order to evaporate materials, which maytypically be solvents or diluents of various types, from the hydrogelseparator precursor mixture, and then the dispensed and appliedmaterials may be cured. It may be possible to repeat both of theprocesses depicted at FIG. 8B and FIG. 8C in combination in someexamples. In some examples, the hydrogel separator precursor mixture maybe cured by exposure to heat while in other examples the curing may beperformed by exposure to photon energy. In still further examples thecuring may involve both exposure to photon energy and to heat. There maybe numerous manners to cure the hydrogel separator precursor mixture.

The result of curing may be to form the hydrogel separator precursormaterial to the wall of the cavity as well as the surface region inproximity to an anode or cathode feature which in the present examplemay be an anode feature. Adherence of the material to the sidewalls ofthe cavity may be useful in the separation function of a separator. Theresult of curing may be to form an anhydrous polymerized precursormixture concentrate 822 which may be simply considered the separator ofthe cell. Proceeding to FIG. 8D, cathode slurry 830 may be depositedonto the surface of the laminar construct release layer 802. Next, atFIG. 8E the cathode slurry 830 may be squeegeed into the cathode pocketand onto the anhydrous polymerized precursor mixture concentrate 822.The cathode slurry may be moved to its desired location in the cavitywhile simultaneously being cleaned off to a large degree from thelaminar construct release layer 802. The process of FIG. 8E may beperformed several times to ensure coating of the cathode slurry 830 ontop of the anhydrous polymerized precursor mixture concentrate 822.Next, at FIG. 8F, the cathode slurry may be allowed to dry down to forman isolated cathode fill 832 on top of the anhydrous polymerizedprecursor mixture concentrate 822, filling in the remainder of thecathode pocket.

Proceeding to FIG. 8G, an electrolyte formulation 840 may be added on tothe isolated cathode fill 832 and allowed to hydrate the isolatedcathode fill 832 and the anhydrous polymerized precursor mixtureconcentrate 822. Next, at FIG. 8H, a cathode connection foil 816 may beadhered to the remaining laminar construct adhesive layer 804 byremoving the remaining laminar construct release layer 802 and pressingthe connection foil 816 in place. The resulting placement may result incovering the hydrated cathode fill 842 as well as establishingelectrical contact to the cathode fill 842 as a cathode currentcollector and connection means.

FIGS. 9A through 9C may illustrate an alternative example of theresulting laminate assembly from FIG. 7D. In FIG. 9A, the anodeconnection foil 710 may be obtained and a protective masking layer 712applied to one side. The anode connection foil 710 may be plated with alayer 714 of coherent metal with, for example, zinc. In similar fashionas described in the previous figures. Proceeding to FIG. 9B, a hydrogelseparator 910 may be applied without the use of the squeegee methodillustrated in FIG. 8E. The hydrogel separator precursor mixture may beapplied in various manners, for example, a preformed film of the mixturemay be adhered by physical adherence; alternatively, a diluted mixtureof the hydrogel separator precursor mixture may be dispensed and thenadjusted to a desired thickness by the processing of spin coating.Alternatively the material may be applied by spray coating, or any otherprocessing equivalent. Next, at FIG. 9C, processing is depicted tocreate a segment of the hydrogel separator that may function as acontainment around a separator region. The processing may create aregion that limits the flow, or diffusion, of materials such aselectrolyte outside the internal structure of the formed batteryelements. Such a blocking feature 920 of various types may therefore beformed. The blocking feature, in some examples, may correspond to ahighly crosslinked region of the separator layer as may be formed insome examples by increased exposure to photon energy in the desiredregion of the blocking feature 920. In other examples, materials may beadded to the hydrogel separator material before it is cured to createregionally differentiated portions that upon curing become the blockingfeature 920. In still further examples, regions of the hydrogelseparator material may be removed either before or after curing byvarious techniques including, for example, chemical etch of the layerwith masking to define the regional extent. The region of removedmaterial may create a blocking feature in its own right or alternativelymaterially may be added back into the void to create a blocking feature.The processing of the impermeable segment may occur through severalmethods including image out processing, increased cross-linking, heavyphotodosing, back-filling, or omission of hydrogel adherence to create avoid. In some examples, a laminate construct or assembly of the typedepicted as the result of the processing in FIG. 9C may be formedwithout the blocking feature 920.

Polymerized Battery Element Separators

In some battery designs, the use of a discrete separator (as describedin a previous section) may be precluded due to a variety of reasons suchas the cost, the availability of materials, the quality of materials, orthe complexity of processing for some material options as non-limitingexamples. In such cases, a cast or form-in-place separator which isillustrated in the processes of FIGS. 8A-8H, for example, may providedesirable benefits. While starch or pasted separators have been usedcommercially with success in AA and other format Leclanché orzinc-carbon batteries, such separators may be unsuitable in some waysfor use in certain examples of laminar microbatteries. Particularattention may need to be paid to the uniformity and consistency ofgeometry for any separator used in the batteries of the presentinvention. Precise control over separator volume may be needed tofacilitate precise subsequent incorporation of known cathode volumes andsubsequent realization of consistent discharge capacities and cellperformance.

A method to achieve a uniform, mechanically robust form-in-placeseparator may be to use UV-curable hydrogel formulations. Numerouswater-permeable hydrogel formulations may be known in variousindustries, for example, the contact lens industry. An example of acommon hydrogel in the contact lens industry may bepoly(hydroxyethylmethacrylate) crosslinked gel, or simply pHEMA. Fornumerous applications of the present invention, pHEMA may possess manyattractive properties for use in Leclanché and zinc-carbon batteries.pHEMA typically may maintain a water content of approximately 30-40percent in the hydrated state while maintaining an elastic modulus ofabout 100 psi or greater. Furthermore, the modulus and water contentproperties of crosslinked hydrogels may be adjusted by one of skill inthe art by incorporating additional hydrophilic monomeric (e.g.methacrylic acid) or polymeric (e.g. polyvinylpyrrolidone) components.In this manner, the water content, or more specifically, the ionicpermeability of the hydrogel may be adjusted by formulation.

Of particular advantage in some examples, a castable and polymerizablehydrogel formulation may contain one or more diluents to facilitateprocessing. The diluent may be chosen to be volatile such that thecastable mixture may be squeegeed into a cavity, and then allowed asufficient drying time to remove the volatile solvent component. Afterdrying, a bulk photopolymerization may be initiated by exposure toactinic radiation of appropriate wavelength, such as blue UV light at420 nm, for the chosen photoinitiator, such as CGI 819. The volatilediluent may help to provide a desirable application viscosity so as tofacilitate casting a uniform layer of polymerizable material in thecavity. The volatile diluent may also provide beneficial surface tensionlowering effects, particularly in the case where strongly polar monomersare incorporated in the formulation. Another aspect that may beimportant to achieve the casting of a uniform layer of polymerizablematerial in the cavity may be the application viscosity. Common smallmolar mass reactive monomers typically do not have very highviscosities, which may be typically only a few centipoise. In an effortto provide beneficial viscosity control of the castable andpolymerizable separator material, a high molar mass polymeric componentknown to be compatible with the polymerizable material may be selectedfor incorporation into the formulation. Examples of high molar masspolymers which may be suitable for incorporation into exemplaryformulations may include polyvinylpyrrolidone and polyethylene oxide.

In some examples the castable, polymerizable separator may beadvantageously applied into a designed cavity, as previously described.In alternative examples, there may be no cavity at the time ofpolymerization. Instead, the castable, polymerizable separatorformulation may be coated onto an electrode-containing substrate, forexample, patterned zinc plated brass, and then subsequently exposed toactinic radiation using a photomask to selectively polymerize theseparator material in targeted areas. Unreacted separator material maythen be removed by exposure to appropriate rinsing solvents. In theseexamples, the separator material may be designated as aphoto-patternable separator.

Primary Battery Example

In some examples of the processing of biocompatible energizationelements with deposited separators, a primary battery may be formed. Atypical primary battery may be characterized by its single-use property.In an example consistent with the laminar processing a battery may beformed with the following characteristics and elements.

Element Material Cathode Current collector Brass Cathode (Slurry)Electrolytic Manganese Dioxide Base Separator Hydrogel AnodeElectrodeposited Zinc Anode Current collector Brass LaminatePolyethylene Terphalate Base Electrolyte ZnCl2/NH4CL Base

There may be numerous formulations of cathode chemistry that may beconsistent with this disclosure. As a non-limiting example, aformulation may comprise Electrolytic Manganese Dioxide in a Graphitemixture. In an example a powder mixture may be formed by mixing JetMilled Electrolytic Manganese Dioxide (JMEMD) and KS6 graphite asavailable from Timcal (TIMCAL TIMREX® KS6 Primary Synthetic Graphite) ina 80 percent JMEMD to 20 percent KS6 ratio by weight. The mixing may beperformed by numerous means, as an example the JMEMD and KS6 may bemixed by grind milling the two powders for an extended period. In someexamples, the resulting powder mixture may be mixed with a 10 percentPolyisobutylene (PIB) in Toluene solution. The 10 percent PIB solutionmay be formed from Polyisobutylene grade B50 mixed with toluene in aroughly 10 parts PIB B50 to 90 parts toluene formulation by weight. The10 percent PIB may be mixed with an additional amount of toluene andwith the JMEMD/K6 powder to formulate a slurry for cathode processing.This mixture may include these materials in a ratio of roughly 1.5 partsPIB B50/Toluene solution to 2.3 parts Toluene to 4.9 parts JMEMD/KS6powder. The mixing may proceed until a uniform slurry with a pastelikeconsistency is formed. The amount of solvent (toluene in an example) inthe system may be varied to affect the characteristics of the slurryformed, and in other examples the relative amount of PIB B50 in theslurry may be varied from the example.

Continuing with the primary battery example, a hydrogel separator may beformed in the manners discussed in this disclosure from a precursormixture. An example of a precursor mixture may be formed by mixinghydroxyethylmethacrylate (HEMA); with ethylene glycol dimethylacrylate(EGDMA); and with polyvinylpyrrolidone (PVP). There may be otherconstituents added to the mixture such as photoinitiators. An exemplaryphotoinitiator may be phenylbis(2,4,6-trimethylbenzoyl)-phosphine oxidewhich may be available in commercial formulations including Irgacure®819 which may also be called CGI 819 herein. There may also be numeroussolvents that may be used in varying amounts to reach a desired rheologyof the mixture. In a non-limiting example, 2-proponol may be used as anappropriate solvent.

Many of the general discussions on elements of biocompatibleenergization devices such as the cathode and cathode slurry haveexamples related to primary battery elements and the variations andexamples for these various elements may be expected to comprise otherexamples of primary battery elements for the present specification.

In some examples, the zinc anode may be formed by electrodepositing thezinc upon the contact material. In other examples, as have beendiscussed, the electrodeposition may occur through the laminatestructure to only exposed portions of the contact material. There may benumerous manners of depositing anode materials and other battery systemsmay employ other chemical species other than zinc such as silver as anon-limiting example.

The battery may include various types of electrolyte formulations. Basicsolution on hydroxide may be included in the electrolyte. However, insome examples of biocompatible batteries less basic electrolyteformulations may be utilized. Electrolytes for use in the presentinvention may include zinc chloride, zinc acetate, ammonium acetate, andammonium chloride in mass concentrations from approximately 0.1 percentto 25 percent. As a non-limiting example a 5 wt. percent solution ofzinc chloride and ammonium chloride may be dissolved in water as a base.In addition, surfactants may be added to the electrolyte formulation.Exemplary surfactants may include Triton™ X-100, Triton™ QS44, andDowfax™ 3B2 in concentrations from 0.01 percent to 2 percent. As anexample Triton™ X-100 may be added to the zinc chloride, ammoniumchloride solution.

Secondary Battery Examples

The structure and manufacturing processes that have been described inthe present disclosure may be useful in general for the production ofsecondary batteries. There may be a number of considerations related tosecondary battery elements that may differ from considerations made forprimary elements. The recharging process for a battery element mayresult in swelling and shrinking of battery components, and thereforethe dimensions of features and containment layers as well as thecomposition of the battery may be adjusted in some embodiments. The useof gelled polymer layers for the electrolytes may allow for a layerwhich may take up some of the swelling and shrinking aspects aselectrode ions are moved around the device during charging cycles, andsubsequently, during discharging cycles.

In secondary batteries, the anode and cathode layers may switchdesignation depending on whether the device is charging or discharging,and may be considered first and second electrodes. Therefore, it may beuseful to refer to the anode and cathode in reference to whether thebattery cell is being charged such that it may be considered anelectrolytic cell or whether it is being discharged such that it may beconsidered a galvanic cell. Therefore, when referred to as the cathodeof the galvanic cell, the first electrode structure would function tospontaneously accept electrons from an externally connected circuit. Aswell, the cathode of the electrolytic cell is physically the secondelectrode in the secondary battery which accepts electrons from anexternal charging element.

Although in some examples the zinc manganese dioxide class of batteriescan function as a secondary battery, there are many more common examplesof secondary batteries. In a common class of secondary batteries,lithium ions may comprise the energy storing chemical species. There maybe numerous manners to form electrodes in lithium ion batteries. In thetype of devices according to the present disclosure, there may benumerous intercalated lithium compounds that might be present in theanode of the galvanic cell. For example, the cathode slurry may includeLithium Nickel Manganese Cobalt Oxide, Lithium Manganese Oxide, andLithium Iron Phosphate amongst others.

The second electrode may be the anode of the galvanic cell and, in someexamples, may be formed of or coated with graphite or other forms ofcarbon. In other examples, various forms of deposited silicon may beused. In similar manners to the electroplating of zinc discussed withrespect to primary batteries, silicon may be electroplated either inregions or in a flat layer across the substrate. Electroplated siliconmay be formed onto the current collector layer which may have surfacecoatings of platinum, titanium or a thin layer of silicon in someexamples. The platting of the electrode material may occur innon-aqueous media comprising SiCl4, SiHCL3, SiBr4, Si(Ch2Ch3)4, orSi(OOCCH3)4 as non-limiting examples. In other examples, graphite orsilicon layers may be sputter deposited to the current collector surfaceto form the second electrode region in a manner similar to that depictedat FIG. 7D.

The electrodes may be formed upon metal sheets in manners consistentwith the prior discussions relating to laminate processing. Theseelectrodes and metal sheets may form the base layer: i.e. underneath thelaminate layers that form the cavity. Also, the current collectorconnected to the other electrode may be used to cap the laminatestructure after the cathode has been formed and the cell has been filledwith electrolyte.

To form electrolyte solutions, lithium salts may typically be dissolvedin non-aqueous solvent systems. Therefore, these non-aqueous solventsystems may interact with the various adhesive layers in differentmanners, and since the integrity of seals in the battery devices may beimportant, there may be alterations in the choice of adhesive systemsthat may be required depending on the use of non-aqueous solvents.Gelled forms of polymer electrolytes are known in lithium polymerdevices incorporating polymer electrolytes. The methods of formation ofseparators starting with liquid precursor filling of a cavity may beperformed for these types of secondary batteries where a polymerizedseparator may be formed from polymers such as PVDF orpoly(acrylonitrile). In some examples, it may be possible to utilizehydrogel forming precursors where the polymer is gelled withconventional salts consistent with Lithium cells. For example, in anon-limiting example a separator precursor may be mixed with lithiumhexafluorophosphate in non-aqueous solvents such as ethylene carbonate,dimethyl carbonate, and diethyl carbonate as non-limiting examples. Theresulting gelled layer may be formed with excess solvent to allow forshrinkage as has been described in relationship to the hydrogelprecursor processing.

In a specific non-limiting example, a cavity-based laminate structuremay be formed, as has been described in the prior discussion of laminateprocessing, where the bottom layer may be the current collector uponwhich a graphite or silicon layer has been attached. The laminate layersthat attach to the current collector may have the cavities formed intothem as has been described. In a non-limiting example, a castingsolution may be formed by mixing a roughly two to one ratio ofpoly(vinylidene fluoride) (PVDF) and poly(dimethylsiloxane) (PDMS) intoa solvent mixture comprising N—N Dimethyl Acetamide (DMAc) and glycerol.The ratio of the DMAc to glycerol may be varied and may affectcharacteristics such as the porosity of the resulting separator layer.An excess of the solvent mixture may be used to allow for the shrinkageof the resulting layer in the cavity to form a thin separator layer. Insome examples, especially for high levels of solvent, the adhesivesystem for the laminate structure may be altered to optimize consistencywith the DMAc-glycerol solvent system. After squeegee processing of thecasting solution into the defined cavities, the resulting structure maybe dried at room temperature or elevated temperature for some timeperiod. Other manners of dispensing the casting solution may beconsistent with the processes described herein. Thereafter, thestructure may be immersed into a room temperature water bath for 20-40hours to allow for the glycerol to dissolve out of the separator layerand result in a layer with a desired porosity. The resulting structuremay then be dried in a vacuum environment over a period of 20-40 hours.

In some examples, the resulting separator layer may be treated withexposure to an electrolyte solution. In a non-limiting example a 1 MolarLithium Hexafluorophosphate solution in a roughly 1/1/1 mixture ofEthylene Carbonate (EC)/Dimethyl Carbonate (DMC) and Ethyl MethylCarbonate (EMC) may be formed and dispensed into the cavity. In someother examples exposure to the electrolyte may occur after the cathodeis formed into the cavity.

In a different type of example the laminate structure may be built inthe manner outlined in reference to FIGS. 4A-4N. A separator, such as afilm of Celgard may be cut to a size of a feature in a gap spacer layerand then placed into the laminate structure as opposed to being filedinto the cavity. The placed separator may also be treated with anexposure to electrolyte before further processing with a “cathodeslurry”.

The resulting structure may now be ready to receive a treatment with thecathode slurry. A number of cathode slurries comprising different typesof lithium compounds may be used; although, other chemical types thanlithium may be possible. In a non-limiting example, a lithium ironphosphate (LiFePO4) based slurry may be used. In some examples thelithium iron phosphate slurry may be formed by first mixing sodiumcarboxymethyl cellulose in deionized water. To the resulting mixture, apowder comprising Lithium Iron Phosphate and conductive agents such assynthetic graphite and carbon black may then be added and extensivelymixed. Next a further refined slurry may be formed by adding styrenebutadiene rubber and extensively mixing. The slurry may then beprocessed into the cavity structure in means as have been described inthe present disclosure such as through use of a squeegee process. Therheology of the slurry may be adjusted for optimizing the integrity ofthe squeegee based filing process for example, by adding or removingsolvent or by adjusting the relative amount of the styrene butadienerubber added. The resulting filled structure may then be dried in avacuum environment over 20-40 hours.

In some examples, the resulting cathode and separator layers may betreated with exposure to an electrolyte solution. In a non-limitingexample a 1 Molar Lithium Hexafluorophosphate solution in a roughly1/1/1 mixture of Ethylene Carbonate (EC)/Dimethyl Carbonate (DMC) andEthyl Methyl Carbonate (EMC) may be formed and dispensed into thecavity. In some examples, the electrolyte may be added to the cathodewith the assistance of either pressure treatment or vacuum treatment toenhance the diffusion of the electrolyte mixture into the layers.

The second current collector layer may be attached to the laminatestructure after the removal of a release layer from laminate structure.The adhered current collector may contact the deposited slurry andprovide electrical contact between the metal current collector and theelectrolyte infused cathode resulting in a battery structure.

Multi-Battery Interconnection Aspects

The laminar structure based on cavities creates a natural battery devicethat has multiple individual battery elements. There may be numerousadvantages to battery devices that comprise individual elements such ashas been described in U.S. patent application Ser. No. 13/358,916, filedon Jan. 26, 2012, (now U.S. Pat. No. 9,110,310), entitled MULTIPLEENERGIZATION ELEMENTS IN STACKED INTEGRATED COMPONENT DEVICES, thecontents of which are incorporated herein by reference. Referring toFIG. 10A, exemplary electrical interconnects for multi-battery elementsare be depicted. Eleven individual battery cavities may be depicted asbattery elements 1010-1020. Each battery element may have acorresponding trace that leads away from a battery to a interconnectjunction element 1025. For example, battery element 1010 may haveinterconnect 1001, and independent battery element 1011 may have anindependent interconnect 1002. The traces may be routed independentlywith electrical isolation until they reach the interconnect junctionelement 1025. In some examples, all eleven batteries may have a commonground connection on the back of the multi-battery element. In otherexamples, each of the individual battery elements may have a similarindependent second contact as is depicted for the first contact in FIG.10A.

Proceeding to FIG. 10B an alternative example is depicted for elevensimilar battery elements. As an example, the first battery element 1010may be again depicted in FIG. 10B as with dotted lines to indicate thata different scheme of interconnect routing may be employed. In FIG. 10Bthe routing lines may be spatially contained to be above or below thebattery elements, where the interconnect junction 1026 may therefore addto the height of the device, rather than to the width as may be the casewith FIG. 10A.

The interconnect junction devices 1025 or 1026 may comprise variousdevices. In some of the simpler examples, the interconnect junctiondevice may merely provide routing connections amongst the interconnectswhich may be useful, amongst other things, for defining multiple batteryvoltages. In a next set of interconnect junction element examples, theelement may contain interconnects and diode structures. The diodes maybe standard PN junction diodes or, in other more preferred examples, maybe low forward drop diodes such as Schottky diodes. The diodes mayprovide a passive means to isolate a defective or lower-capacity elementfrom other devices. For example, each battery may have differentopen-circuit and loaded voltages, impedance, and discharge capacity.These differences may arise from slights differences in processing,assembly, storage, and aging or may arise from significant defects inthe cells. For example, each battery's positive/cathode output mayconnect to a common node and a similar connection scheme may beperformed for the anodes. In such an example, in which all batteries aredirectly connected in parallel, “strong” batteries, which may have highvoltage and low internal resistance, may discharge through “weak”batteries, which may have low voltage and internal shorts. In such aparallel connection example, the performance of all batteries may bepulled to a “lowest common demonimator.” In an extreme example all maydischarge through a single cell having an internal short. Alternatively,examples in which the cathode/positive terminal of each battery isconnected to a common node through a diode may limit reduction inperformance. In such examples, in the event of a weak cell, the diodemay limit the reverse current so that one cell cannot degrade the wholearray. In some more intricate examples, integrated circuits may be addedthat may provide more sophisticated control over defective elements andmay provide programmable means to create controlled output voltages ofvarious kinds which may exceed the maximum voltage output of any simpleadditive combination of elements.

Proceeding to FIGS. 10C and 10D, examples in cross section correspondingto the examples in FIG. 10A and FIG. 10B are illustrated. At FIG. 10C, across section corresponding to some examples of FIG. 10 A may be found.A battery cathode 842 located in a cavity in a laminate structure mayhave a cathode contact 1031 and an anode contact 816. The individualbattery elements may have singulated cathode contacts 1031 where metalmay be removed in patterns between the battery elements formingisolation features 1030. An aerial view of the cathode contact mayreveal that the battery cathode contact 1031 may be cut out in such afashion that it has a routing interconnect feature for each individualcathode contact. Proceeding to FIG. 10D, a more complicated interconnectstructure may be employed wherein an insulator layer 1040 may havecontact vias cut into its structure to allow for the contact via 1050.In some examples, the cathode contacts 1031, the isolation features1030, and the isolation layer 1040 may all comprise a laminate layerthat may be added to the battery device in manners as have beendescribed in earlier sections. In some examples, a conductive paste oradhesive may be added to the contact via structure to create a contactvia 1050. Thereafter, interconnect routing lines such as interconnect1001 may be created to electrically connect the battery elements tofeatures such as the interconnect junction element. In some examples,there may be multiple interconnect junction elements for a collection ofbattery elements.

Referring to FIG. 10E, an illustration of a cross section of the batteryelements, 1010 and 1011 of FIG. 1013 is illustrated. A cathode spacerlayer may be formed from the laminar construct core 706, located betweenthe two laminar construct adhesive layers 704 and 704 a. A first hole inthe cathode spacer layer contains a battery cathode fill 842 and asecond hole in the cathode spacer layer contains the battery cathodefill 842. The independent interconnect 1002 at battery element 1011represents a third current collector, wherein the third currentcollector is physically segmented from the second current collector ofbattery element 1010. The third current collector which is independentinterconnect 1002 is in electrical connection with the cathode chemicalswithin the second hole located in the cathode spacer layer.

Voltage Supply Aspects of Multi-Battery Units

In some examples of devices with multiple energization units, thecombination of the batteries into different series and parallelconnections may define different embodiments. When two energizationunits are connected in a series manner, the voltage output of theenergization elements add to give a higher voltage output. When twoenergization units are connected in a parallel manner, the voltageremains the same but the current capacities add together, ideallydoubling the capacity of a single cell while also reducing the internalresistance by half. It may be apparent that in some embodiments, theinterconnection of energization elements may be hardwired into thedesign of the element. However, in other embodiments, the elements maybe combined through use of switching elements to define different powersupply conditions that may be dynamically defined.

Proceeding to FIG. 11, an example of how switches (including theexemplary switches 1120-1122, 1130, 1140-1145, 1150, 1160-1165, 1170,and 1180-1185) may be used to define up to 4 different voltage suppliesfrom the switched combination of four different energization elementsare shown. It may be apparent that the number of elements provided is anexemplary sense and that many different combinations would definesimilar art within the spirit of the inventive art herein. As well,items 1101, 1102, 1103 and 1104 may define the ground connections offour different energization elements, or in some embodiments these mayrepresent the ground connections of four different banks of energizationelements as was demonstrated in the description of FIG. 8. In anexemplary sense, items 1105, 1106, 1107 and 1109 may define biasconnections to each of the four depicted energization elements where thebias connection may assume a nominal voltage condition which may be 1.5volts higher than the individual element ground connections, 1101,1102,1103 and 1104.

As shown in FIG. 11, there may be a microcontroller, item 1116, that isincluded in the energized device which, among its various controlconditions, may control the number of power supplies that the multipleenergization units are connected to define. In some embodiments, themicrocontroller may connect to a switch controller, item 1115, which mayindex control signal level changes from the microcontroller into statechanges to the individual switches. For ease of presentation, the outputof item 1115 is shown as a single item 1110. In this set of embodiments,this signal is meant to represent the individual control lines that goout to the variety of switches depicted as items 1120 through 1185.There may be numerous types of switches that are consistent with thespirit of the inventive art herein, however in a non-limiting sense, theswitches may be MOSFET switches in an exemplary sense. It may beapparent that any of the numerous mechanical and electrical typeswitches or other switch types that may be controlled by an electricalsignal may comprise art within the spirit of the inventive art herein.

According to the circuit embodiment of FIG. 11, the control of theswitches may be used to generate a number of different voltageconditions. As a starting example, the switches may be configured sothat there are two different voltage conditions defined: both the 1.5volt condition shown as item 1113 and the 3 volt condition shown as item1112. There are numerous ways for this to happen; but for example, thefollowing manner will be described where two different elements are usedfor each of the voltage conditions. One may consider combining theelements represented by their ground connections of item 1101 and 1102as the 1.5 volt supply elements. For this to occur, item 1105, the biasconnection for the first energization element may be observed to alreadyconnect to the 1.5 volt supply line item 1113. For the secondenergization element bias connection 1106 to connect to supply line1113, switch 1142 may be turned to a connected state while switches1143, 1144 and 1145 may be configured in a non-connected state. Theground connection of the second energization element may now beconnected to the ground line, 1114 by activating switch 1130. To definethe second supply line 1112, the 3 volt supply line, the common/groundconnections of the third 1103 and forth 1104 elements may be connectedto the 1.5 volt supply line 1113. For this to be enacted for the thirdelement, switch 1121 may be activated, whereas switches 1120 and 1122may be deactivated. This may cause connection 1103 to be at the 1.5 voltcondition of element 1113. Switch 1150 may be deactivated in this case.For the fourth element, switch 1140 may be activated. Switch 1141 mayalso be activated; however, if it is inactive, the same condition mayexist. Switch 1170 may be deactivated so that the connection to theground line is not made.

The bias connections of the third 1107 and forth 1109 elements may nowbe connected to the 3 volt power line 1113. For the third elementconnection, switch 1163 should be active while switches 1162, 1164 and1165 may be inactivated. For the fourth element 1109, switch 1183 may beactive while switches 1182, 1184, and 1185 may be inactive. This set ofconnections may define one of the embodiments that may result in such atwo-level (1.5 and 3 Volt) rough power supply condition through theexemplary use of 4 energization units.

The embodiments that may derive from the connections illustrated in FIG.11 may result in a number of different power supply conditions that mayresult from the use of four energization elements or four banks ofenergization elements. It may be apparent that many more connections ofenergization elements may be consistent with the inventive art herein.In a non-limiting sense, there may be as few as two energizationelements or any number more than that, which may be consistent with anenergized device. In any of these embodiments, there may be similarconcepts for switching the connections of the ground and bias side ofthe energization elements into parallel and series connection, which mayresult in multiples of the energization voltage of the individualenergization element voltage. The description of a type of embodimentutilizing the switching infrastructure of FIG. 11 may, in someembodiments, describe a set of connections that may be programmed intoan energized device and then utilized for the lifetime of the resultingdevice embodiment. For example, an energized device may have operationalmodes programmed where the number or nature of its power supplies maydynamically change. In a non-limiting exemplary sense, referring to FIG.11, item 1110 may represent a power supply line of the device where, insome modes, the device is not connected to any energization elementconnections as may be the case if switches 1145, 1165 and 1185 are in anon-activated connection. Other embodiments of this type may result inthe connection of one or more of switches 1145, 1165, and 1185 resultingin a defined energization voltage for the power-supply of item 1110.This dynamic activation of a particular voltage may also includedeactivation at a later time, or alternatively, a dynamic change toanother operating energization voltage. There may be a significantdiversity of operational embodiments that may derive from the inventiveart herein when energized devices are included with multipleenergization elements, which may be connected in static and dynamicmanners to other elements of the energized device.

Multiple Energization Elements in Energized Devices

Proceeding to FIG. 12, item 1200, a schematic representation of anembodiment with a battery element of the type shown in FIG. 10A, isillustrated. The multiple energization elements that were identified asitems 1010-1020 in FIG. 10A may now be represented by individualidentifiers associated with batteries. It may be apparent that thenumber and organization of the multiple elements are but one of manydifferent arrangements and are depicted for illustrative purposes.Nevertheless, in some embodiments as shown, the elements may be arrangedin banks. In FIG. 12, a first bank of elements may therefore include1210, 1211, 1212 and 1213. A second bank of elements may include items1214, 1215, 1216 and 1217. A third bank of elements may be representedby elements 1218, 1219, and 1220. An antenna element may also bedemonstrated.

In some embodiments, each of these banks may share a common ground linefor the three or four elements that are connected in the bank. Forillustrative purposes, bank one, including items 1210, 1211, 1212 and1213, may share a common ground line: shown as item 1230. Additionally,each of the elements may then have a separate line connecting them to aninterconnect element, which may be represented by the circuit element1290. It may be clear that numerous differences in the connection,count, and the make-up of each battery element may comprise art withinthe scope of this inventive art. Also, it may be possible that eachbattery element has both a common and a biased electrode separatelyconnected to the interconnect layer.

As mentioned, in some embodiments where banks of battery elements sharea common ground, that battery element 1213 may share a common connection1230 and also have its own bias connection 1235. These connections mayinterface with the interconnection element 1290 and then continue on toa power management element identified in this figure as item 1205. Thetwo connections may have corresponding input connections into the powermanagement unit where 1240 may be a continuation of the bank. A commonground connection 1230 and item 1245 may be a continuation of thebattery element 1213 bias connection 1235. Thus, the individual batteryelement may be connected to the power management entity, and switchesmay control how it is electrically connect to further elements. In someembodiments, the three banks of eleven multiple energization units mayall in fact be connected in a parallel fashion. The parallel fashion maygenerate a raw battery power supply that has the same voltage conditionof the battery elements and a combined battery capacity of the elevenunits. The power management unit 1205 may connect each of the elevenelements 1210-1220 in such a parallel fashion. In alternativeembodiments, the power management element may refine and alter the inputpower to result in a refined power output that will be supplied to therest of the energized device. It may be apparent that numerouselectrical refinements may be performed by the power management element,including in a non-limiting sense, regulating all the elements to matcha standard reference voltage output; multiplying the voltage of theindividual elements; regulating the current outputted by the combinedbattery elements; and many other such refinements.

In some embodiments, the raw output of the power management unit may beconnected to the interconnection layer as shown by element 1250. Thispower supply may be passed through the interconnection device andelectrically fed to an integrated passive device element (IPD) 1206which may be connected to the multiple-battery element. Within theintegrated passive device element 1206, there may be capacitors. The rawpower supply connection that comes from the interconnect 1255 may beused to charge the capacitors to the voltage condition of the raw powersupply. In some embodiments, the charging may be controlled by an activeelement; in other embodiments, it may just be passed onto the capacitorelement. The resulting connection of the capacitor may then beidentified as a first power supply condition.

Capacitors may be placed into the integrated passive device element tostore energy for use by the various electroactive elements. In otherexamples, the capacitors may be included as part of the power managementdevice itself or on the other components that are drawing power from thepower management device. In still further examples, capacitors may beincluded into the overall device both as passive elements as well asintegrated elements in other devices such as the power managementdevice.

There may be numerous motivations for conditioning the power provided bymultiple energization units. An exemplary motivation, in someembodiments, may derive from the power requirements of the componentsthat are connected. If these elements have different operating statesthat require different current conditions, then the current draw of thehighest operating state current draw may be buffered by the presence ofthe capacitors. Thus, the capacitors may store significantly morecurrent capacity then the eleven battery elements may be able to provideat a given point in time. Depending on the conditions of the currentdrawing element, and of the nature of the capacitors in the IPD item1206, there may still be a limitation of the amount of time during whicha transient high current drawing state may occur and not overwhelm thebattery. Since the capacitors would need to be recharged after a highdraw on their current capacity, it may be obvious that there may need tobe a sufficient time between reoccurrences of the high current drawcondition. Therefore, it may be clear that there could be a large numberof different design aspects relating to (1) the number of energizationunits, (2) their energy capacities, (3) the types of devices theyconnect to, and (4) the design power requirements of the elements thatare provided energy by (a) these energization elements, (b) the powermanagement system, and (c) the integrated passive devices.

Self-Testing and Reliability Aspects of Multiple Energization Units

The nature of energization elements may include aspects where when theelements are assembled into energized devices they may have failuremodes that may have the nature of an initial or “time zero” failure; oralternatively, be an aged failure where an initially functioning elementmay fail during the course of its use. The characteristics of energizedcomponent devices with multiple energization elements allow forembodiments of circuitry and design which allow for remediating suchfailure modes and maintaining a functional operational state.

Returning to FIG. 12, some embodiments of self-testing and repair may beillustrated in an exemplary sense. Consider an embodiment type where theeleven multiple energization elements, 1210 to 1220 are all connected ina parallel manner to define one power supply condition based on thestandard operating voltage of each element. As mentioned, the nature ofcombining these multiple number of energization elements may allow theEnergized Device to perform self-testing and repair if an energizationunit is defective or becomes defective. A sensing element may be used todetect the current flowing through the energization devices.

There may be numerous ways to set a condition in the energized devicewhere its current may be at a standard value. In an exemplary sense, thedevice could have a “Sleep mode” that it activates where the quiescentcurrent draw is at a very low value. The sensing protocol may be asstraightforward as inserting a resistive element into the power-supplyground return line; although, more sophisticated means of measuringcurrent flow, including magnetic or thermal transducers or any othermeans of performing electrical current metrology, may be consistent withthe spirit of the art herein. If the diagnostic measurement of thecurrent flow (in some embodiments represented as a voltage drop throughthe resistive element compared to a reference voltage) is found toexceed a standard tolerance, then the exemplary self-test circuitry mayproceed to determine if one of the energization elements is causing theexcessive current draw condition. In proceeding, one exemplary manner ofisolating the cause may be to first cycle through isolating one of thefour banks at a time by disconnecting its ground return line. Referringback to FIG. 12, the bank of elements 1210, 1211, 1212 and 1213 may bethe first bank to be isolated. Ground line 1230 may be disconnected. Thesame electrical current draw metrology may next be performed after theisolation. If the current sensed has now returned to a normal currentdraw, then the problem may be indicated to occur in that bank. If,alternatively, the current still remains out of a specified conditionthen the logical looping process may proceed to the next bank. It may bepossible that after looping through all the banks, which in thisexemplary sense may be three banks, the current draw is still outside ofthe normal tolerance. In such a case, and in some embodiments, theself-testing protocol may then exit its test of the energizationelements and then either stop self-testing or initiate self-testing forsome other potential current draw issue. In describing this self-testingprotocol, it may be apparent that an exemplary protocol has beendescribed to illustrate the concepts of the inventive art herein, andthat numerous other protocols may result in a similar isolation ofindividual energization units which may be malfunctioning.

Proceeding with the exemplary protocol, when a defect has been found andisolated and then the current flow during the testing returns to anormal specification, a next isolation loop may be performed. Now that aproblem has been isolated to an individual bank, the next checks mayisolate a defective element within that bank. Therefore, the individualbank may again be activated; however, each of the four elements, forexample 1210, 1211, 1212 and 1213, may have their bias connectiondisconnected. In FIG. 12, 1235 may represent the bias connection ofelement 1213 and if it were a defective part, when the bank is activatedit will draw significant current until its bias connection isdisconnected. So, after an element is isolated, the current draw mayagain be sensed. If the isolation of an element returns the current drawto a normal state, then that element may be indicated as defective andsubsequently disconnected from the power supply system.

If the second looping process continues through all energizationelements in a bank without the current returning to an acceptable value,the loop may end. In such an event, the self-test circuitry may thenproceed to disable the entire bank from the power supply system; or inother embodiments, it may proceed with a different manner of isolatingelements in the bank. There may be numerous manners to defineself-diagnostic protocols for multiple energization units and theactions that are programed to occur based on these protocols.

Rechargeable Elements in Multiple Energization Units

Remaining still with FIG. 12, another set of embodiments that may resultfrom integrating multiple energization elements into energized devicesmay be seen where the energization elements may be recharged. In someembodiments, where there are multiple energization elements (such asitems 1210 to 1220) and there are elements within the energized devicethat may be useful for recharging an energization element, there may bethe ability to charge some of the elements.

In an exemplary set of embodiments, an energized device containingmultiple energization elements may be capable of receiving andprocessing RF signals from an antenna 1270 comprised within its device.In some embodiments, there may exist a second antenna 1291, which may beuseful for receiving wireless energy (e.g. inductive energy transfer,RF, light, and the like) from the environment of the device and passingthis energy to a power management device, 1205. In an exemplary sense,there may be included a microcontroller element 1255, which may bothdraw power from the energized device's energization units and alsocontrol the operations within the device. This microcontroller 1255 mayprocess information that has been inputted to it using programmedalgorithms to determine that the energization system of the elevenelements, 1210 to 1220, may have enough energy to support the powerrequirements of the current device function. This processing may occurwhere only a subset of the elements are being used to power the supplycontrolling circuitry of the power management device, In such examples,the remaining elements may then be connected to the charging circuitry1245 of the power management component which may be receiving the power,as mentioned previously, that is being received by antenna 1291. Forexample, in the embodiment depicted in FIG. 12, the energized device maybe placed into a state where three of the multiple energizationelements, items 1218, 1219 and 1220, may be connected to the chargingelectronics. Simultaneously, the remaining 8 elements, items 1210 to1217 may be connected to the supply circuitry, 1240. In this manner, anenergized device with energization may be enabled, through the use ofmultiple energization elements, to operate in modes where the elementsare both being charged and discharged simultaneously.

Single Use Energization Elements with Electroactive Elements.

Proceeding to FIG. 13, an example of a biocompatible device withmultiple energization elements, where the energization elements areintended for single use, is depicted. In some examples, the energizationelements may be batteries formed in laminate film processing withcavities. In some examples, there may be eleven battery elements shownas 1310 to 1320. The elements may be arranged into banks wherein eachbank may have a common ground line and separate biased connections. Theground and bias connections may be routed through an interconnectjunction element 1330. The interconnect junction element may connect topower control systems 1340, controller systems 1350, and various routingdevices 1360. The device may receive external signals from a sensingelement 1305. The device may provide controlling signals to anelectroactive device element 1390 through interconnects 1355. In someexamples, the electroactive device may be an electroactive focusing lensin a biocompatible ophthalmic device such as a contact lens. The singleuse battery elements may be sensed for working status and combined andacted up in power management circuits to ensure an operating life, evenif some of the single use energization elements are not functional. Thesensing element may be used to receive an activation signal and/or alevel change signal which may change the status of the electroactiveelement.

The biocompatible devices can be, for example, implantable electronicdevices, such as pacemakers and micro-energy harvesters, electronicpills for monitoring and/or testing a biological function, surgicaldevices with active components, ophthalmic devices, microsized pumps,defibrillators, stents, and the like.

Specific examples have been described to illustrate embodiments for theformation, methods of formation, and apparatus of formation ofbiocompatible energization elements comprising separators. Theseexamples are for said illustration and are not intended to limit thescope of the claims in any manner. Accordingly, the description isintended to embrace all embodiments that may be apparent to thoseskilled in the art.

What is claimed is:
 1. An apparatus for powering a biomedical device, the apparatus comprising: a laminate battery device with multiple energization elements for a biomedical device including powered components, comprising: a cathode spacer layer, wherein the cathode spacer layer comprises a laminar construct core located adjacent to at least a first laminar construct adhesive layer; a first hole located in the cathode spacer layer; a first current collector coated with anode chemicals, wherein the first current collector is attached to the first laminar construct adhesive layer of the cathode spacer layer, and wherein a first cavity is created between sides of the first hole and a first surface of the first current collector coated with anode chemicals; a separator layer, wherein the separator layer is formed within the first cavity after a separator precursor mixture is dispensed into the first cavity; a second cavity between sides of the first hole and a first surface of the separator layer, wherein the second cavity is filled with cathode chemicals within the second cavity; a first independent interconnect, wherein the first independent interconnect is in electrical connection with the cathode chemicals within the second cavity; a second independent interconnect, wherein the second independent interconnect is physically segmented from the first independent interconnect and is in electrical connection with cathode chemicals within a third cavity; wherein the third cavity is within a second hole located in the cathode spacer layer; and an interconnect junction element, wherein the interconnection junction element makes electrical connection to the first current collector, the first independent interconnect, and the second independent interconnect, wherein an electrical diode within the interconnect junction element makes connection to at least one of the first current collector, the the first independent interconnect, and the second independent interconnect. 